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• What are the tools needed in order to create a GUI application?

  - by iownfloppydisk

  in more easy way except the netbeans generated codes because i don't like the codes they generated.

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• Sequential WSASend() calls - can I rely on TCP to put them on the wire in the posting order?

  - by Poni

  On Windows I/O completion ports, say I do this: void function() { WSASend("1111"); // A WSASend("2222"); // B WSASend("3333"); // C } If I got a "write-complete" that says 3 bytes of WSASend() A were sent, is it possible that right after that I'll get a "write-complete" that tells me that some or all of B & C were sent, or will TCP will hold them until I re-issue a WSASend() call with the rest of A's data? Or will TCP complete it automatically?

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• how to set the tab order for the UI controls in win 32?

  - by Rakesh

  hello all I have a small dialog which I created dynamically, which has a textbox and a button..if the user presses the TAB key it has to switch between the two control(textbox and button)...I tried using SetwindowPos...but it doesnt seem to solve my problem...please give me a solution for this..in the below code..I also tried to include the mainwindow in the taborder..still it doesnt work //dialog creation HWND dialogHandle = CreateWindowEx(0,WC_DIALOG,L"Security Alert",WS_OVERLAPPEDWINDOW|WS_VISIBLE,600,300,280,160,NULL,NULL,NULL,NULL); //create textboxcontrol within the dialog HWND textBoxHandle = CreateWindowEx(WS_EX_CLIENTEDGE,L"EDIT",L"",WS_CHILD|WS_VISIBLE |ES_PASSWORD | WS_TABSTOP,123,48,110,25,dialogHandle,(HMENU)IDD_TEXTBOX,NULL,NULL); //create button HWND buttonHandle = CreateWindowEx(NULL,L"Button",L"OK",WS_CHILD|WS_VISIBLE| WS_TABSTOP,151,85,85,25,dialogHandle,(HMENU)ID_PASSWORD_OK,NULL,NULL); //setwindowpos SetWindowPos(NULL,textBoxHandle,0,0,0,0,SWP_NOMOVE|SWP_NOSIZE); SetWindowPos(textBoxHandle,buttonHandle,0,0,0,0,SWP_NOMOVE|SWP_NOSIZE);

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• How to insert rows in a many-to-many relationship

  - by GSound

  Hello, I am having an issue trying to save into an intermediate table. I am new on Rails and I have spent a couple of hours on this but can't make it work, maybe I am doing wrong the whole thing. Any help will be appreciated. =) The app is a simple book store, where a logged-in user picks books and then create an order. This error is displayed: NameError in OrderController#create uninitialized constant Order::Orderlist These are my models: class Book < ActiveRecord::Base has_many :orderlists has_many :orders, :through => :orderlists end class Order < ActiveRecord::Base belongs_to :user has_many :orderlists has_many :books, :through => :orderlists end class OrderList < ActiveRecord::Base belongs_to :book belongs_to :order end This is my Order controller: class OrderController < ApplicationController def add if session[:user] book = Book.find(:first, :conditions => ["id = #{params[:id]}"]) if book session[:list].push(book) end redirect_to :controller => "book" else redirect_to :controller => "user" end end def create if session[:user] @order = Order.new if @order.save session[:list].each do |b| @order.orderlists.create(:book => b) # <-- here is my prob I cant make it work end end end redirect_to :controller => "book" end end Thnx in advance! Manuel

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• Why does the order of the loops affect performance when iterating over a 2D array? [closed]

  - by Mark

  Possible Duplicate: Which of these two for loops is more efficient in terms of time and cache performance Below are two programs that are almost identical except that I switched the i and j variables around. They both run in different amounts of time. Could someone explain why this happens? Version 1 #include <stdio.h> #include <stdlib.h> main () { int i,j; static int x[4000][4000]; for (i = 0; i < 4000; i++) { for (j = 0; j < 4000; j++) { x[j][i] = i + j; } } } Version 2 #include <stdio.h> #include <stdlib.h> main () { int i,j; static int x[4000][4000]; for (j = 0; j < 4000; j++) { for (i = 0; i < 4000; i++) { x[j][i] = i + j; } } }

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• C# setting case constant expressions, do they have to follow a specific order?

  - by Umeed

  Say I'm making a simple program, and the user is in the menu. And the menu options are 1 3 5 7 (i wouldn't actually do that but lets just go with it). and I want to make my switch statement using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace DecisionMaking2 { class Program { static void Main(string[] args) { Console.WriteLine("Please choose an option: "); string SelectedOpt = Console.ReadLine(); double Selection = Convert.ToDouble(SelectedOpt); double MenuOption = (Selection); switch (MenuOption) { case 1: Console.WriteLine("Selected option #1"); break; case 2: Console.WriteLine("Selected option #3"); break; case 3: Console.WriteLine("Selected option #5"); break; case 4: Console.WriteLine("Selected option #7"); break; default: Console.WriteLine("Please choose from the options List!"); break; } } } } would that work? or would I have to name each case constant expression the option number I am using? I went to the microsoft website and I didn't quite pick up on anything i was looking for. . Also while I have your attention, how would I make it so the user chooses from either option and because I don't know which option the user will select " double MenuOption = " could be anything, whatever the user inputs right? so would what I have even work? I am doing this all by hand, and don't get much lab time to work on this as I have tons of other courses to work on and then a boring job to go to, and my PC at home has a restarting issue lol. soo any and all help is greatly appreciated. p.s the computer I'm on right now posting this, doesn't have any compilers, coding programs, and it's not mine just to get that out of the way. Thanks again!

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• XSLT : I need to parse the xml with same element name with sequence of order to map in to another xml with different name

  - by Karuna

  As the below source XML Value/string element value has to be replace with target element value, Could some please help me out how to create the XSL to transform from source xml into target xml .Please. Source XML: <PricingResultsV6> <subItems> <SubItem> <profiles> <ProfileValues> <values> <strings>800210</strings> <strings>THC</strings> <strings>10.0</strings> <strings>20.0</strings> <strings>30.0</strings> <strings>40.0</strings> <strings>550.0</strings> <strings>640.0</strings> </values> </ProfileValues> </rofiles> </SubItem> </subItems> </PricingResultsV6> Target XML : <CalculationOutput> <PolicyNumber> 800210 </PolicyNumber> <CommissionFactorMultiplier> THC </CommissionFactorMultiplier> <PremiumValue>10.0</PremiumValue> <SalesmanCommissionValue>20.0</SalesmanCommissionValue> <ManagerCommissionValue>30.0</ManagerCommissionValue> <GL_COR> 550.0</GL_COR> <GL_OPO>640.0</GL_OPO> </CalculationOutput>

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• Check if an object is order-able in python?

  - by sortfiend

  How can I check if an object is orderable/sortable in Python? I'm trying to implement basic type checking for the __init__ method of my binary tree class, and I want to be able to check if the value of the node is orderable, and throw an error if it isn't. It's similar to checking for hashability in the implementation of a hashtable. I'm trying to accomplish something similar to Haskell's (Ord a) => etc. qualifiers. Is there a similar check in Python?

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• A Taxonomy of Numerical Methods v1

  - by JoshReuben

  Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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• DCOGS Balance Breakup Diagnostic in OPM Financials

  - by ChristineS-Oracle

  Purpose of this diagnostic (OPMDCOGSDiag.sql) is to identify the sales orders which constitute the Deferred COGS account balance.This will help to get the detailed transaction information for Sales Order/s Order Management, Account Receivables, Inventory and OPM financials sub ledger at the Organization level.  This script is applicable for various scenarios of Standard Sales Order, Return Orders (RMA) coupled with all the applicable OPM costing methods like Standard, Actual and Lot costing.  OBJECTIVE: The sales order(s) which are at different stages of their life cycle in one spreadsheet at one go. To collect the information of: This will help in: Lesser time for data collection. Faster diagnosis of the issue. Easy collaboration across different modules like  Order Management, Accounts Receivables, Inventory and Cost Management.  You can download the script from Doc ID 1617599.1 DCOGS Balance Breakup (SO/RMA) and Diagnostic Analyzer in OPM Financials.

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• Could you recommend a good shopping cart script?

  - by user649482

  I'm looking for a PHP/MySQL script, free or not. Could you please recommend me one that can do the following: The site I'm trying to build requires an extensive product catalogue, which will have around 600 products. Because there are so many products they will be uploaded using a CSV file or spreadsheet. Users must be logged in to see prices Users can add products to an order form, which they can then email to admin. (NO payment processing whatsoever) They will just add products to a cart, review the cart's content and click a button to send the order The order email to admin must have the order details attached in a CSV file. Newsletter Newsletter sign up. Admin can create and send newsletter from the admin section. User Login/Member Section After users sign up they can access their member section. In this section they can Edit their details See previous orders they have made, and click a button to send that order again Thank you! (the question is also posted here but with no replies)

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• Toon shader with Texture. Can this be optimized?

  - by Alex

  I am quite new to OpenGL, I have managed after long trial and error to integrate Nehe's Cel-Shading rendering with my Model loaders, and have them drawn using the Toon shade and outline AND their original texture at the same time. The result is actually a very nice Cel Shading effect of the model texture, but it is havling the speed of the program, it's quite very slow even with just 3 models on screen... Since the result was kind of hacked together, I am thinking that maybe I am performing some extra steps or extra rendering tasks that maybe are not needed, and are slowing down the game? Something unnecessary that maybe you guys could spot? Both MD2 and 3DS loader have an InitToon() function called upon creation to load the shader initToon(){ int i; // Looping Variable ( NEW ) char Line[255]; // Storage For 255 Characters ( NEW ) float shaderData[32][3]; // Storate For The 96 Shader Values ( NEW ) FILE *In = fopen ("Shader.txt", "r"); // Open The Shader File ( NEW ) if (In) // Check To See If The File Opened ( NEW ) { for (i = 0; i < 32; i++) // Loop Though The 32 Greyscale Values ( NEW ) { if (feof (In)) // Check For The End Of The File ( NEW ) break; fgets (Line, 255, In); // Get The Current Line ( NEW ) shaderData[i][0] = shaderData[i][1] = shaderData[i][2] = float(atof (Line)); // Copy Over The Value ( NEW ) } fclose (In); // Close The File ( NEW ) } else return false; // It Went Horribly Horribly Wrong ( NEW ) glGenTextures (1, &shaderTexture[0]); // Get A Free Texture ID ( NEW ) glBindTexture (GL_TEXTURE_1D, shaderTexture[0]); // Bind This Texture. From Now On It Will Be 1D ( NEW ) // For Crying Out Loud Don't Let OpenGL Use Bi/Trilinear Filtering! ( NEW ) glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexImage1D (GL_TEXTURE_1D, 0, GL_RGB, 32, 0, GL_RGB , GL_FLOAT, shaderData); // Upload ( NEW ) } This is the drawing for the animated MD2 model: void MD2Model::drawToon() { float outlineWidth = 3.0f; // Width Of The Lines ( NEW ) float outlineColor[3] = { 0.0f, 0.0f, 0.0f }; // Color Of The Lines ( NEW ) // ORIGINAL PART OF THE FUNCTION //Figure out the two frames between which we are interpolating int frameIndex1 = (int)(time * (endFrame - startFrame + 1)) + startFrame; if (frameIndex1 > endFrame) { frameIndex1 = startFrame; } int frameIndex2; if (frameIndex1 < endFrame) { frameIndex2 = frameIndex1 + 1; } else { frameIndex2 = startFrame; } MD2Frame* frame1 = frames + frameIndex1; MD2Frame* frame2 = frames + frameIndex2; //Figure out the fraction that we are between the two frames float frac = (time - (float)(frameIndex1 - startFrame) / (float)(endFrame - startFrame + 1)) * (endFrame - startFrame + 1); // I ADDED THESE FROM NEHE'S TUTORIAL FOR FIRST PASS (TOON SHADE) glHint (GL_LINE_SMOOTH_HINT, GL_NICEST); // Use The Good Calculations ( NEW ) glEnable (GL_LINE_SMOOTH); // Cel-Shading Code // glEnable (GL_TEXTURE_1D); // Enable 1D Texturing ( NEW ) glBindTexture (GL_TEXTURE_1D, shaderTexture[0]); // Bind Our Texture ( NEW ) glColor3f (1.0f, 1.0f, 1.0f); // Set The Color Of The Model ( NEW ) // ORIGINAL DRAWING CODE //Draw the model as an interpolation between the two frames glBegin(GL_TRIANGLES); for(int i = 0; i < numTriangles; i++) { MD2Triangle* triangle = triangles + i; for(int j = 0; j < 3; j++) { MD2Vertex* v1 = frame1->vertices + triangle->vertices[j]; MD2Vertex* v2 = frame2->vertices + triangle->vertices[j]; Vec3f pos = v1->pos * (1 - frac) + v2->pos * frac; Vec3f normal = v1->normal * (1 - frac) + v2->normal * frac; if (normal[0] == 0 && normal[1] == 0 && normal[2] == 0) { normal = Vec3f(0, 0, 1); } glNormal3f(normal[0], normal[1], normal[2]); MD2TexCoord* texCoord = texCoords + triangle->texCoords[j]; glTexCoord2f(texCoord->texCoordX, texCoord->texCoordY); glVertex3f(pos[0], pos[1], pos[2]); } } glEnd(); // ADDED THESE FROM NEHE'S FOR SECOND PASS (OUTLINE) glDisable (GL_TEXTURE_1D); // Disable 1D Textures ( NEW ) glEnable (GL_BLEND); // Enable Blending ( NEW ) glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); // Set The Blend Mode ( NEW ) glPolygonMode (GL_BACK, GL_LINE); // Draw Backfacing Polygons As Wireframes ( NEW ) glLineWidth (outlineWidth); // Set The Line Width ( NEW ) glCullFace (GL_FRONT); // Don't Draw Any Front-Facing Polygons ( NEW ) glDepthFunc (GL_LEQUAL); // Change The Depth Mode ( NEW ) glColor3fv (&outlineColor[0]); // Set The Outline Color ( NEW ) // HERE I AM PARSING THE VERTICES AGAIN (NOT IN THE ORIGINAL FUNCTION) FOR THE OUTLINE AS PER NEHE'S TUT glBegin (GL_TRIANGLES); // Tell OpenGL What We Want To Draw for(int i = 0; i < numTriangles; i++) { MD2Triangle* triangle = triangles + i; for(int j = 0; j < 3; j++) { MD2Vertex* v1 = frame1->vertices + triangle->vertices[j]; MD2Vertex* v2 = frame2->vertices + triangle->vertices[j]; Vec3f pos = v1->pos * (1 - frac) + v2->pos * frac; Vec3f normal = v1->normal * (1 - frac) + v2->normal * frac; if (normal[0] == 0 && normal[1] == 0 && normal[2] == 0) { normal = Vec3f(0, 0, 1); } glNormal3f(normal[0], normal[1], normal[2]); MD2TexCoord* texCoord = texCoords + triangle->texCoords[j]; glTexCoord2f(texCoord->texCoordX, texCoord->texCoordY); glVertex3f(pos[0], pos[1], pos[2]); } } glEnd (); // Tell OpenGL We've Finished glDepthFunc (GL_LESS); // Reset The Depth-Testing Mode ( NEW ) glCullFace (GL_BACK); // Reset The Face To Be Culled ( NEW ) glPolygonMode (GL_BACK, GL_FILL); // Reset Back-Facing Polygon Drawing Mode ( NEW ) glDisable (GL_BLEND); } Whereas this is the drawToon function in the 3DS loader void Model_3DS::drawToon() { float outlineWidth = 3.0f; // Width Of The Lines ( NEW ) float outlineColor[3] = { 0.0f, 0.0f, 0.0f }; // Color Of The Lines ( NEW ) //ORIGINAL CODE if (visible) { glPushMatrix(); // Move the model glTranslatef(pos.x, pos.y, pos.z); // Rotate the model glRotatef(rot.x, 1.0f, 0.0f, 0.0f); glRotatef(rot.y, 0.0f, 1.0f, 0.0f); glRotatef(rot.z, 0.0f, 0.0f, 1.0f); glScalef(scale, scale, scale); // Loop through the objects for (int i = 0; i < numObjects; i++) { // Enable texture coordiantes, normals, and vertices arrays if (Objects[i].textured) glEnableClientState(GL_TEXTURE_COORD_ARRAY); if (lit) glEnableClientState(GL_NORMAL_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); // Point them to the objects arrays if (Objects[i].textured) glTexCoordPointer(2, GL_FLOAT, 0, Objects[i].TexCoords); if (lit) glNormalPointer(GL_FLOAT, 0, Objects[i].Normals); glVertexPointer(3, GL_FLOAT, 0, Objects[i].Vertexes); // Loop through the faces as sorted by material and draw them for (int j = 0; j < Objects[i].numMatFaces; j ++) { // Use the material's texture Materials[Objects[i].MatFaces[j].MatIndex].tex.Use(); // AFTER THE TEXTURE IS APPLIED I INSERT THE TOON FUNCTIONS HERE (FIRST PASS) glHint (GL_LINE_SMOOTH_HINT, GL_NICEST); // Use The Good Calculations ( NEW ) glEnable (GL_LINE_SMOOTH); // Cel-Shading Code // glEnable (GL_TEXTURE_1D); // Enable 1D Texturing ( NEW ) glBindTexture (GL_TEXTURE_1D, shaderTexture[0]); // Bind Our Texture ( NEW ) glColor3f (1.0f, 1.0f, 1.0f); // Set The Color Of The Model ( NEW ) glPushMatrix(); // Move the model glTranslatef(Objects[i].pos.x, Objects[i].pos.y, Objects[i].pos.z); // Rotate the model glRotatef(Objects[i].rot.z, 0.0f, 0.0f, 1.0f); glRotatef(Objects[i].rot.y, 0.0f, 1.0f, 0.0f); glRotatef(Objects[i].rot.x, 1.0f, 0.0f, 0.0f); // Draw the faces using an index to the vertex array glDrawElements(GL_TRIANGLES, Objects[i].MatFaces[j].numSubFaces, GL_UNSIGNED_SHORT, Objects[i].MatFaces[j].subFaces); glPopMatrix(); } glDisable (GL_TEXTURE_1D); // Disable 1D Textures ( NEW ) // THIS IS AN ADDED SECOND PASS AT THE VERTICES FOR THE OUTLINE glEnable (GL_BLEND); // Enable Blending ( NEW ) glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); // Set The Blend Mode ( NEW ) glPolygonMode (GL_BACK, GL_LINE); // Draw Backfacing Polygons As Wireframes ( NEW ) glLineWidth (outlineWidth); // Set The Line Width ( NEW ) glCullFace (GL_FRONT); // Don't Draw Any Front-Facing Polygons ( NEW ) glDepthFunc (GL_LEQUAL); // Change The Depth Mode ( NEW ) glColor3fv (&outlineColor[0]); // Set The Outline Color ( NEW ) for (int j = 0; j < Objects[i].numMatFaces; j ++) { glPushMatrix(); // Move the model glTranslatef(Objects[i].pos.x, Objects[i].pos.y, Objects[i].pos.z); // Rotate the model glRotatef(Objects[i].rot.z, 0.0f, 0.0f, 1.0f); glRotatef(Objects[i].rot.y, 0.0f, 1.0f, 0.0f); glRotatef(Objects[i].rot.x, 1.0f, 0.0f, 0.0f); // Draw the faces using an index to the vertex array glDrawElements(GL_TRIANGLES, Objects[i].MatFaces[j].numSubFaces, GL_UNSIGNED_SHORT, Objects[i].MatFaces[j].subFaces); glPopMatrix(); } glDepthFunc (GL_LESS); // Reset The Depth-Testing Mode ( NEW ) glCullFace (GL_BACK); // Reset The Face To Be Culled ( NEW ) glPolygonMode (GL_BACK, GL_FILL); // Reset Back-Facing Polygon Drawing Mode ( NEW ) glDisable (GL_BLEND); glPopMatrix(); } Finally this is the tex.Use() function that loads a BMP texture and somehow gets blended perfectly with the Toon shading void GLTexture::Use() { glEnable(GL_TEXTURE_2D); // Enable texture mapping glBindTexture(GL_TEXTURE_2D, texture[0]); // Bind the texture as the current one }

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• Snake Game Help

  - by MuhammadA

  I am making a snake game and learning XNA at the same time. I have 3 classes : Game.cs, Snake.cs and Apple.cs My problem is more of a conceptual problem, I want to know which class is really responsible for ... detecting collision of snake head on apple/itself/wall? which class should increase the snakes speed, size? It seems to me that however much I try and put the snake stuff into snake.cs that game.cs has to know a lot about the snake, like : -- I want to increase the score depending on size of snake, the score variable is inside game.cs, which means now I have to ask the snake its size on every hit of the apple... seems a bit unclean all this highly coupled code. or -- I DO NOT want to place the apple under the snake... now the apple suddenly has to know about all the snake parts, my head hurts when I think of that. Maybe there should be some sort of AppleLayer.cs class that should know about the snake... Whats the best approach in such a simple scenario? Any tips welcome. Game.cs : using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using Microsoft.Xna.Framework.Design; namespace Snakez { public enum CurrentGameState { Playing, Paused, NotPlaying } public class Game1 : Microsoft.Xna.Framework.Game { private GraphicsDeviceManager _graphics; private SpriteBatch _spriteBatch; private readonly Color _niceGreenColour = new Color(167, 255, 124); private KeyboardState _oldKeyboardState; private SpriteFont _scoreFont; private SoundEffect _biteSound, _crashSound; private Vector2 _scoreLocation = new Vector2(10, 10); private Apple _apple; private Snake _snake; private int _score = 0; private int _speed = 1; public Game1() { _graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { _spriteBatch = new SpriteBatch(GraphicsDevice); _scoreFont = Content.Load<SpriteFont>("Score"); _apple = new Apple(800, 480, Content.Load<Texture2D>("Apple")); _snake = new Snake(Content.Load<Texture2D>("BodyBlock")); _biteSound = Content.Load<SoundEffect>("Bite"); _crashSound = Content.Load<SoundEffect>("Crash"); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { Content.Unload(); } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState newKeyboardState = Keyboard.GetState(); if (newKeyboardState.IsKeyDown(Keys.Escape)) { this.Exit(); // Allows the game to exit } else if (newKeyboardState.IsKeyDown(Keys.Up) && !_oldKeyboardState.IsKeyDown(Keys.Up)) { _snake.SetDirection(Direction.Up); } else if (newKeyboardState.IsKeyDown(Keys.Down) && !_oldKeyboardState.IsKeyDown(Keys.Down)) { _snake.SetDirection(Direction.Down); } else if (newKeyboardState.IsKeyDown(Keys.Left) && !_oldKeyboardState.IsKeyDown(Keys.Left)) { _snake.SetDirection(Direction.Left); } else if (newKeyboardState.IsKeyDown(Keys.Right) && !_oldKeyboardState.IsKeyDown(Keys.Right)) { _snake.SetDirection(Direction.Right); } _oldKeyboardState = newKeyboardState; _snake.Update(); if (_snake.IsEating(_apple)) { _biteSound.Play(); _score += 10; _apple.Place(); } base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(_niceGreenColour); float frameRate = 1 / (float)gameTime.ElapsedGameTime.TotalSeconds; _spriteBatch.Begin(); _spriteBatch.DrawString(_scoreFont, "Score : " + _score, _scoreLocation, Color.Red); _apple.Draw(_spriteBatch); _snake.Draw(_spriteBatch); _spriteBatch.End(); base.Draw(gameTime); } } } Snake.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public enum Direction { Up, Down, Left, Right } public class Snake { private List<Rectangle> _parts; private readonly Texture2D _bodyBlock; private readonly int _startX = 160; private readonly int _startY = 120; private int _moveDelay = 100; private DateTime _lastUpdatedAt; private Direction _direction; private Rectangle _lastTail; public Snake(Texture2D bodyBlock) { _bodyBlock = bodyBlock; _parts = new List<Rectangle>(); _parts.Add(new Rectangle(_startX, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + bodyBlock.Width, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 2, _startY, _bodyBlock.Width, _bodyBlock.Height)); _parts.Add(new Rectangle(_startX + (bodyBlock.Width) * 3, _startY, _bodyBlock.Width, _bodyBlock.Height)); _direction = Direction.Right; _lastUpdatedAt = DateTime.Now; } public void Draw(SpriteBatch spriteBatch) { foreach (var p in _parts) { spriteBatch.Draw(_bodyBlock, new Vector2(p.X, p.Y), Color.White); } } public void Update() { if (DateTime.Now.Subtract(_lastUpdatedAt).TotalMilliseconds > _moveDelay) { //DateTime.Now.Ticks _lastTail = _parts.First(); _parts.Remove(_lastTail); /* add new head in right direction */ var lastHead = _parts.Last(); var newHead = new Rectangle(0, 0, _bodyBlock.Width, _bodyBlock.Height); switch (_direction) { case Direction.Up: newHead.X = lastHead.X; newHead.Y = lastHead.Y - _bodyBlock.Width; break; case Direction.Down: newHead.X = lastHead.X; newHead.Y = lastHead.Y + _bodyBlock.Width; break; case Direction.Left: newHead.X = lastHead.X - _bodyBlock.Width; newHead.Y = lastHead.Y; break; case Direction.Right: newHead.X = lastHead.X + _bodyBlock.Width; newHead.Y = lastHead.Y; break; } _parts.Add(newHead); _lastUpdatedAt = DateTime.Now; } } public void SetDirection(Direction newDirection) { if (_direction == Direction.Up && newDirection == Direction.Down) { return; } else if (_direction == Direction.Down && newDirection == Direction.Up) { return; } else if (_direction == Direction.Left && newDirection == Direction.Right) { return; } else if (_direction == Direction.Right && newDirection == Direction.Left) { return; } _direction = newDirection; } public bool IsEating(Apple apple) { if (_parts.Last().Intersects(apple.Location)) { GrowBiggerAndFaster(); return true; } return false; } private void GrowBiggerAndFaster() { _parts.Insert(0, _lastTail); _moveDelay -= (_moveDelay / 100)*2; } } } Apple.cs : using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework; namespace Snakez { public class Apple { private readonly int _maxWidth, _maxHeight; private readonly Texture2D _texture; private readonly Random random = new Random(); public Rectangle Location { get; private set; } public Apple(int screenWidth, int screenHeight, Texture2D texture) { _maxWidth = (screenWidth + 1) - texture.Width; _maxHeight = (screenHeight + 1) - texture.Height; _texture = texture; Place(); } public void Place() { Location = GetRandomLocation(_maxWidth, _maxHeight); } private Rectangle GetRandomLocation(int maxWidth, int maxHeight) { // x and y -- multiple of 20 int x = random.Next(1, maxWidth); var leftOver = x % 20; x = x - leftOver; int y = random.Next(1, maxHeight); leftOver = y % 20; y = y - leftOver; return new Rectangle(x, y, _texture.Width, _texture.Height); } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw(_texture, Location, Color.White); } } }

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• How do I make a jumping dolphin rotate realistically?

  - by Johnny

  I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. At the moment, my dolphin rotates a little weird. But I want that it rotates like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation += 0.01f; VelocityY += 40f; } else { rotation -= 0.01f; VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { rotation -= 0.01f; VelocityY += -10f; } else { rotation += 0.01f; VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } } I changed my code a little. But I still have some trouble with the rotation. Here's the entire code. The dolphin looks at the wrong direction if I press the left or right key. For example, it looks down if I press the left key. What is wrong with the rotation? At the beginning, the dolphin looks at the left side, but after I pressed a key it just looks down or up. I deleted the "rotation += 0.01f;" lines in the code. Is that correct? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); Vector2 prevPos; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } rotation = (float)Math.Atan2(Position.X - prevPos.X, Position.Y - prevPos.Y); prevPos = Position; // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { VelocityY += 40f; } else { VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { VelocityY += -10f; } else { VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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• algorithm analysis - orders of growth question

  - by cchampion

  I'm studing orders of growth "big oh", "big omega", and "big theta". Since I can't type the little symbols for these I will denote them as follows: ORDER = big oh OMEGA = big omega THETA = big theta For example I'll say n = ORDER(n^2) to mean that the function n is in the order of n^2 (n grows at most as fast n^2). Ok for the most part I understand these: n = ORDER(n^2) //n grows at most as fast as n^2 n^2 = OMEGA(n) //n^2 grows atleast as fast as n 8n^2 + 1000 = THETA(n^2) //same order of growth Ok here comes the example that confuses me: what is n(n+1) vs n^2 I realize that n(n+1) = n^2 + n; I would say it has the same order of growth as n^2; therefore I would say n(n+1) = THETA(n^2) but my question is, would it also be correct to say: n(n+1) = ORDER(n^2) please help because this is confusing to me. thanks.

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• Spring MVC - Cannot map request parameters as a Map parameter in method?

  - by Ken Chen

  What I want to do is passing a map to the method in Controller using @RequestParam, but it seems not working. While this is working in Struts 2. Below is what I am trying: In JSP using JQuery: var order = {}; order['seq'] = "ASC"; var criteria = {}; criteria['label'] = "Directory"; $.post(context + 'menu/list', {"orders" : order, "criterias" : criteria} The parameters I am trying to post is an 'map' object order and criteria for listing menu. In Java: @RequestMapping("/{collection}/list") public @ResponseBody Map<String, ? extends Object> list(@PathVariable String collection, @RequestParam("criterias") Map<String, String> criteria, @RequestParam("orders") Map<String, String> order) { However, when I print out the map criteria & order in Java, it takes all value as below: Criteria: {criterias[label]=Directory, orders[seq]=ASC} Order: {criterias[label]=Directory, orders[seq]=ASC} Can @RequestParam in Spring be used to init a Map parameter?

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• Ingame menu is not working correctly

  - by Johnny

  The ingame menu opens when the player presses Escape during the main game. If the player presses Y in the ingame menu, the game switches to the main menu. Up to here, everything works. But: On the other hand, if the player presses N in the ingame menu, the game should switch back to the main game(should resume the main game). But that doesn't work. The game just rests in the ingame menu if the player presses N. I set a breakpoint in this line of the Ingamemenu class: KeyboardState kbState = Keyboard.GetState(); CurrentSate/currentGameState and LastState/lastGameState have the same state: IngamemenuState. But LastState/lastGameState should not have the same state than CurrentSate/currentGameState. What is wrong? Why is the ingame menu not working correctly? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; IState lastState, currentState; public enum GameStates { IntroState = 0, MenuState = 1, MaingameState = 2, IngamemenuState = 3 } public void ChangeGameState(GameStates newState) { lastGameState = currentGameState; lastState = currentState; switch (newState) { case GameStates.IntroState: currentState = new Intro(this); currentGameState = GameStates.IntroState; break; case GameStates.MenuState: currentState = new Menu(this); currentGameState = GameStates.MenuState; break; case GameStates.MaingameState: currentState = new Maingame(this); currentGameState = GameStates.MaingameState; break; case GameStates.IngamemenuState: currentState = new Ingamemenu(this); currentGameState = GameStates.IngamemenuState; break; } currentState.Load(Content); } public void ChangeCurrentToLastGameState() { currentGameState = lastGameState; currentState = lastState; } public GameStates CurrentState { get { return currentGameState; } set { currentGameState = value; } } public GameStates LastState { get { return lastGameState; } set { lastGameState = value; } } private GameStates currentGameState = GameStates.IntroState; private GameStates lastGameState; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void Initialize() { ChangeGameState(GameStates.IntroState); base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); currentState.Load(Content); } protected override void Update(GameTime gameTime) { currentState.Update(gameTime); if ((lastGameState == GameStates.MaingameState) && (currentGameState == GameStates.IngamemenuState)) { lastState.Update(gameTime); } base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); if ((lastGameState == GameStates.MaingameState) && (currentGameState == GameStates.IngamemenuState)) { lastState.Render(spriteBatch); } currentState.Render(spriteBatch); spriteBatch.End(); base.Draw(gameTime); } } public interface IState { void Load(ContentManager content); void Update(GameTime gametime); void Render(SpriteBatch batch); } public class Intro : IState { Texture2D Titelbildschirm; private Game1 game1; public Intro(Game1 game) { game1 = game; } public void Load(ContentManager content) { Titelbildschirm = content.Load<Texture2D>("gruft"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Space)) game1.ChangeGameState(Game1.GameStates.MenuState); } public void Render(SpriteBatch batch) { batch.Draw(Titelbildschirm, new Rectangle(0, 0, 1280, 720), Color.White); } } public class Menu:IState { Texture2D Choosescreen; private Game1 game1; public Menu(Game1 game) { game1 = game; } public void Load(ContentManager content) { Choosescreen = content.Load<Texture2D>("menubild"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Enter)) game1.ChangeGameState(Game1.GameStates.MaingameState); if (kbState.IsKeyDown(Keys.Escape)) game1.Exit(); } public void Render(SpriteBatch batch) { batch.Draw(Choosescreen, new Rectangle(0, 0, 1280, 720), Color.White); } } public class Maingame : IState { Texture2D Spielbildschirm, axe; Vector2 position = new Vector2(100,100); private Game1 game1; public Maingame(Game1 game) { game1 = game; } public void Load(ContentManager content) { Spielbildschirm = content.Load<Texture2D>("hauszombie"); axe = content.Load<Texture2D>("axxx"); } public void Update(GameTime gametime) { KeyboardState keyboardState = Keyboard.GetState(); float delta = (float)gametime.ElapsedGameTime.TotalSeconds; position.X += 5 * delta; position.Y += 3 * delta; if (keyboardState.IsKeyDown(Keys.Escape)) game1.ChangeGameState(Game1.GameStates.IngamemenuState); } public void Render(SpriteBatch batch) { batch.Draw(Spielbildschirm, new Rectangle(0, 0, 1280, 720), Color.White); batch.Draw(axe, position, Color.White); } } public class Ingamemenu : IState { Texture2D Quitscreen; private Game1 game1; public Ingamemenu(Game1 game) { game1 = game; } public void Load(ContentManager content) { Quitscreen = content.Load<Texture2D>("quit"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Y)) game1.ChangeGameState(Game1.GameStates.MenuState); if (kbState.IsKeyDown(Keys.N)) game1.ChangeCurrentToLastGameState(); } public void Render(SpriteBatch batch) { batch.Draw(Quitscreen, new Rectangle(200, 200, 200, 200), Color.White); } }

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• Projecting a targetting ring using direct3d

  - by JohnB

  I'm trying to draw a "targetting ring" on the ground below a "unit" in a hobby 3d game I'm working on. Basically I want to project a bright red patterned ring onto the ground terrain below the unit. The only approach I can think of is this - Draw the world once as normal Draw the world a second time but in my vertex shader I have the world x,y,z coordinates of the vertex and I can pass in the coordinates of the highlighted unit - so I can calculate what the u,v coordinates in my project texture should be at that point in the world for that vertex. I'd then use the pixel shader to pick pixels from the target ring texture and blend them into the previously drawn world. I believe that should be easy, and should work but it involves me drawing the whole visible world twice as it's hard to determine exactly which polygons the targetting ring might fall onto. It seems a big overhead to draw the whole world twice, once for the normal lit textured ground, and then again just to draw the targetting ring. Is there a better approach that I'm missing?

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• How do I get Linq-to-SQL to refresh its local copy of a database record?

  - by Gary McGill

  Suppose I have an Orders table in my database and a corresponding model class generated by the VS2008 "Linq to SQL Classes" designer. Suppose I also have a stored procedure (ProcessOrder) in my database that I use to do some processing on an order record. If I do the following: var order = dataContext.Orders.Where(o => o.id == orderId).First(); // More code here dataContext.ProcessOrder(orderId); order.Status = "PROCESSED"; dataContext.SubmitChanges(); ...then I'll get a concurrency violation if the ProcessOrder stored proc has modified the order (which is of course very likely), because L2S will detect that the order record has changed, and will fail to submit the changes to that order. That's all fairly logical, but what if I want to update the order record after calling the stored proc? How do I tell L2S to forget about its cached copy and refresh it from the DB?

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• Displaying text letter by letter

  - by Evi

  I am planing to Write a Text adventure and I don't know how to make the text draw letter by letter in any other way than changing the variable from h to he to hel to hell to hello That would be a terrible amount of work since there are tons of dialogue. Here is the source code so far { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D sampleBG; Texture2D TextBG; SpriteFont defaultfont; KeyboardState keyboardstate; public bool spacepress = false; public bool mspress = false; public int textheight = 425; public int rowspace = 40; public string namebox = "(null)"; public string Row1 = "(null)"; public string Row2 = "(null)"; public string Row3 = "(null)"; public string Row4 = "(null)"; public int Dialogue = 0; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferHeight = 600; graphics.PreferredBackBufferWidth = 800; IsMouseVisible = true; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // TODO: use this.Content to load your game content here sampleBG = Content.Load <Texture2D>("SampleBG"); defaultfont = Content.Load<SpriteFont>("SpriteFont1"); TextBG = Content.Load<Texture2D>("textbg"); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState keyboardstate = Keyboard.GetState(); MouseState mousestate = Mouse.GetState(); // Changes Dialgue by pressing Left Mouse Button or Space #region Dialogue changer if (mousestate.LeftButton == ButtonState.Pressed && mspress == false) { mspress = true; Dialogue = Dialogue + 1; } if (mousestate.LeftButton == ButtonState.Released && mspress == true) { mspress = false; } if (keyboardstate.IsKeyDown(Keys.Space) && spacepress == false) { spacepress = true; Dialogue = Dialogue + 1; } if (keyboardstate.IsKeyUp(Keys.Space) && spacepress == true) { spacepress = false; } #endregion // ------------------------------------------------------ // Dialgue Content #region Dialgue if (Dialogue == 1) { Row1 = "Input Text 1 Here."; Row2 = "Input Text 2 Here."; Row3 = "Input Text 3 Here."; Row4 = "Input Text 4 Here."; } if (Dialogue == 2) { Row1 = "Text 1"; Row2 = "Text 2"; Row3 = "Text 3"; Row4 = "Text 4"; } #endregion // ------------------------------------------------------ base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here spriteBatch.Begin(); spriteBatch.Draw(sampleBG, new Rectangle(0, 0, 800, 600), Color.White); spriteBatch.Draw(TextBG, new Rectangle(0, 400, 800, 200), Color.White); spriteBatch.DrawString(defaultfont, Row1, new Vector2(10, (textheight + (rowspace * 0))), Color.Black); spriteBatch.DrawString(defaultfont, Row2, new Vector2(10, (textheight + (rowspace * 1))), Color.Black); spriteBatch.DrawString(defaultfont, Row3, new Vector2(10, (textheight + (rowspace * 2))), Color.Black); spriteBatch.DrawString(defaultfont, Row4, new Vector2(10, (textheight + (rowspace * 3))), Color.Black); spriteBatch.End(); base.Draw(gameTime); } } }

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• .NET chart Datamanipulator

  - by peter

  In .NET C#4.0 with the .NET Chart control I have this code to generate a pie chart: chart.Series[0].ChartType = SeriesChartType.Pie; foreach (Order order in orderCollection) { // If I set point.LegendText = order.UserName, .Group will erase it chart.Series[0].Points.AddXY(order.UserName, order.Total); } chart.DataManipulator.Sort(PointSortOrder.Ascending, "X", "Series1"); chart.DataManipulator.Group("SUM", 1, IntervalType.Months, "Series1"); This works well, it generates a pie chart with the top 10 users showing their total order sum. I would like to set the DataPoints' legendtext to the order.UserName property. The problem is, DataManipulator.Group overwrites the series DataPoints. So if I set the legendtext in the foreach loop, they will be erased after the Group call. And after the Group call, I don't see a way to retrieve the correct UserName for a DataPoint to set the legendtext. What is the best approach for this situation?

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• Is it possible to get anti-alias for Font in Rebol Graphics VID ?

  - by Rebol Tutorial

  Anti-alias works for Draw but I can't see how to get anti-alias for font : is it possible anywhow (including hacking rebol vid ...) because font in the picture generated below is not nice: view layout [ box 278x185 effect [ ; default box face size is 100x100 draw [ anti-alias on ; information for the next draw element (not required) line-width 2.5 ; number of pixels in width of the border pen black ; color of the edge of the next draw element fill-pen radial 100x50 5 55 5 10 10 71.0.6 30.10.10 71.0.6 ; the draw element box ; another box drawn as an effect 15 ; size of rounding in pixels 0x0 ; upper left corner 278x170 ; lower right corner ] ] pad 30x-150 Text "Experiment" font [name: "Impact" size: 24 color: white] image http://www.rebol.com/graphics/reb-logo.gif ]

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• Drawing random circles

  - by ViktorC

  I am trying to draw a cupola circles at random positions in an Android application. I draw them on a bitmap and then draw that bitmap on the canvas. This is the function where a draw the circles: private void drawRandomCircles(int numOfCircles) { Canvas c = new Canvas(b); Paint cPaint = new Paint; cPaitn.setColor(Color.RED); for(int i = 0; i < numOfCircles; i++) { int x = Math.Random % 100; int y = Math.Random % 100; c.drawCircle(x, y, 20, cPaint) } } The Bitmap b is global. And after calling this function I just draw the bitmap in the onDraw method. Now the problem is that I only get one circle drawn on the screen, no matter the size of numOfCircles. Any clue what is happening here?

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• Where to include business logic in a domain driven architecture

  - by Mike C.

  I'm trying to learn effective DDD practices as I go, but had a fundamental question I wanted to get some clarity on. I am using ASP.NET WebForms and I am creating a situation where a user places an order. Upon order submission, the code-behind retrieves the user, builds the order from the inputs on the form, calls the User.PlaceOrder() method to perform add the order object to the user's order collection, and calls the repository to save the record to the database. That is fairly simply and straightforward. Now I need to add logic to send an order confirmation email, and I'm not really sure the proper place to put this code or where to call it. In the olden days I would simply put that code in the code-behind and call it at the same time I was building the order, but I want to get a step closer to solid proper architecture so I wanted to get some information. Thanks for your help!

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• Which substring of the string1 matches with the string2.

  - by Harikrishna

  There are two strings. String str1="Order Number Order Time Trade Number"; String str2="Order Tm"; Then I want to know that str2 matches with which substring in the str1. string regex = Regex.Escape(str2.Replace(@"\ ", @"\s*"); bool isColumnNameMatched = Regex.IsMatch(str1, regex, RegexOptions.IgnoreCase); I am using regex because "Order Tm" will also matches "Order Time".It gives bool value that matches occurred or not. Like str2="Order Tm" then it should return like in the str1,Order Time is the substring where matches is occurred.

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