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  • SQL SERVER Fix : Error : 3117 : The log or differential backup cannot be restored because no files

    I received the following email from one of my readers.Dear Pinal,I am new to SQL Server and our regular DBA is on vacation. Our production database had some problem and I have just restored full database backup to production server. When I try to apply log back I am getting following error. I am sure, [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Computing complex math equations in python

    - by dassouki
    Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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  • '0' inserted when cross-referencing numbered equations in MSWord 2007

    - by Jyotirmoy Bhattacharya
    I am inserting numbered equations using tables and multi-level lists as described in http://blogs.msdn.com/b/microsoft_office_word/archive/2006/10/20/equation-numbering.aspx I want to cross-reference the equations in my text. To do so I go to Insert-Cross reference and among the "Numbered Items" I pick the equation I wish to refer to. The problem is that if I pick the "Insert reference to" as "Paragraph number" a zero is always inserted into my text. The surprising thing is that the hyperlink in the cross-reference points to the correct equation. Also if I choose "Insert reference to" as "Page number" then the correct page numbers are inserted and they are correctly updated too.

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  • Is there a way to convert MS 2010 Equation to Object in MS Equation 3.0?

    - by Teodorescu
    I have a lot of equations (for faculty) written in MS Equation (button from right side) and saved it in .docx format. All good and the best until my professor told me that he has MS 2003 and I have to convert from docx to doc format and the equations must be editable. I don't have enough time to rewrite all the equations in MS Equation 3.0. Is there a way to convert from MS Equation to MS Equation 3.0 Object to be recognized and editable in Word 2003?

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  • How to solve non-linear equations using python

    - by stars83clouds
    I have the following code: #!/usr/bin/env python from scipy.optimize import fsolve import math h = 6.634e-27 k = 1.38e-16 freq1 = 88633.9360e6 freq2 = 88631.8473e6 freq3 = 88630.4157e6 def J(freq,T): return (h*freq/k)/(math.exp(h*freq/(k*T))-1) def equations(x,y,z,w,a,b,c,d): f1 = a*(J(freq1,y)-J(freq1,2.73))*(1-math.exp(-a*z))-(J(freq2,x)-J(freq2,2.73))*(1-math.exp(-z)) f2 = b*(J(freq3,w)-J(freq3,2.73))*(1-math.exp(-b*z))-(J(freq2,x)-J(freq2,2.73))*(1-math.exp(-z)) f3 = c*(J(freq3,w)-J(freq3,2.73))*(1-math.exp(-b*z))-(J(freq1,y)-J(freq1,2.73))*(1-math.exp(-a*z)) f4 = d*(J((freq3+freq1)/2,(y+w)/2)-J((freq3+freq1)/2,2.73))-(J(freq2,x)-J(freq2,2.73))*(1-math.exp(-z)) return (f1,f2,f3,f4) So, I have defined the equations in the above code. However, I now wish to solve the above set of equations using fsolve or other alternative non-linear numerical routine. I tried the following syntax but with no avail: x,y,z,w = fsolve(equations, (1,1,1,1)) I keep getting the error that "x" is not defined. I am executing all commands at the command-line, since I have no idea how to run a batch of commands as above automatically in python. I welcome any advice on how to solve this.

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  • tool for adding parentheses to equations?

    - by jedierikb
    Is there an online tool for adding parentheses to simple math equations? For example, a + b * c into a + (b * c) Those who paid more attention in math class might be able to tackle order of operations for huge equations in their head, but I could often use some help (and verification of my thinking). I often encounter other people's libraries having equations and functions I need for my code, and this would be kind of helpful for debugging and understanding. I was hoping Wolfram Alpha would do this, but the output is not easy to plug back into most programming languages e.g. a + (bc)

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  • solve mathematical equation with 1 unknown (equations are dynamically built)

    - by chris-gr
    Hi, I have to built dynamically equations like following: x + x/3 + (x/3)/4 + (x/3/4)/2 = 50 Now I would like to evaluate this equation and get x. The equation is built dynamically. x is the leaf node in a taxonomy, the other 3 nodes are the super concepts. The divisor represents the number of children of the child nodes. Is there a library that allows to build such equations dynamically and resolve x? Thanks, Chris

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  • Solving Diophantine Equations Using Python

    - by HARSHITH
    In mathematics, a Diophantine equation (named for Diophantus of Alexandria, a third century Greek mathematician) is a polynomial equation where the variables can only take on integer values. Although you may not realize it, you have seen Diophantine equations before: one of the most famous Diophantine equations is: We are not certain that McDonald's knows about Diophantine equations (actually we doubt that they do), but they use them! McDonald's sells Chicken McNuggets in packages of 6, 9 or 20 McNuggets. Thus, it is possible, for example, to buy exactly 15 McNuggets (with one package of 6 and a second package of 9), but it is not possible to buy exactly 16 nuggets, since no non- negative integer combination of 6's, 9's and 20's adds up to 16. To determine if it is possible to buy exactly n McNuggets, one has to solve a Diophantine equation: find non-negative integer values of a, b, and c, such that 6a + 9b + 20c = n. Write an iterative program that finds the largest number of McNuggets that cannot be bought in exact quantity. Your program should print the answer in the following format (where the correct number is provided in place of n): "Largest number of McNuggets that cannot be bought in exact quantity: n"

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  • Treating differential operator as algebraic entity

    - by chappar
    I know that this question is offtopic and don't belong here. But i didn't know somewhere else to ask. So here is the question. I was reading e:the story of a number by Eli Maor, where he treats differential operator as just like any algebraic entity. For example if we have a differential equation like y’’ + 5y’ - 6y = 0. This can be treaed as (D^2 + 5D – 6)y = 0. So, either y = 0 (trivial solution) or (D^2 + 5D – 6) = 0. Factoring out above equation we get (D-1)(D+6)= 0 with solutions as D = 1 and D = -6. Since D does not have any meaning on its own, multiplying by y on both the sides we get Dy = y and Dy = -6y for which the solutions are Ae^x and Be^-6x. Combining these 2 solutions we get Ae^x + Be^-6x. Now my doubt is this approach break when we have an equation like D^2y = 0. Which means y = 0 (again trivial) or D^2 = 0 which means D = 0. Now Dy = y*0 = 0. That means y = C ( a constant). The actual answer should be Cx. I know that it is stupidity to treat D^2 = 0 as D = 0, it led me to doubt the entire process of treating differential equation as algebraic equation. Can someone throw light on this? Or any other site where i might get answer?

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  • How to strike out inside LaTeX equations?

    - by Aamir
    Please see the snippet below and tell me how can I achieve the same strike-out effect as in the main text. I am using the version of LaTeX from the latest Ubuntu repositories. \documentclass{article} \usepackage{ulem} \begin{document} The sout tag works perfect in the \sout{main text area} but not inside the equations. $$ list = [1, \sout{2}, 3, \sout{4}, 5, \sout{6}, 7, \sout{8}, 9, \sout{10}] $$ Any clue? \end{document} Here is LaTeX output

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  • Scared of Calculus - Required to pass Differential Calculus as part of my Computer science major

    - by ke3pup
    Hi guys I'm finishing my Computer science degree in university but my fear of maths (lack of background knowledge) made me to leave all my maths units til' the very end which is now. i either take them on and pass or have to give up. I've passed all my programming units easily but knowing my poor maths skills won't do i've been staying clear of the maths units. I have to pass Differential Calculus and Linear Algebra first. With a help of book named "Linear Algebra: A Modern Introduction" i'm finding myself on track and i think i can pass the Linear Algebra unit. But with differential calculus i can't find a book to help me. They're either too advanced or just too simple for what i have to learn. The things i'm required to know for this units are: Set notation, the real number line, Complex numbers in cartesian form. Complex plane, modulus. Complex numbers in polar form. De Moivre’s Theorem. Complex powers and nth roots. Definition of ei? and ez for z complex. Applications to trigonometry. Revision of domain and range of a function Working in R3. Curves and surfaces. Functions of 2 variables. Level curves.Partial derivatives and tangent planes. The derivative as a difference quotient. Geometric significance of the derivative. Discussion of limit. Higher order partial derivatives. Limits of f(x,y). Continuity. Maxima and minima of f(x,y). The chain rule. Implicit differentiation. Directional derivatives and the gradient. Limit laws, l’Hoˆpital’s rule, composition law. Definition of sinh and cosh and their inverses. Taylor polynomials. The remainder term. Taylor series. Is there a book to help me get on track with the above? Being a student i can't buy too many books hence why i'm looking for a book that covers topics I need to know. The University library has a fairly limited collection which i took as loan but didn't find useful as it was too complex.

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  • Simple 2-color differential image compression

    - by Groo
    Is there an efficient, quick and simple example of doing differential b/w image compression? Or even better, some simple (but lossless) streaming technique which could accept a number of frames as input? I have a simple b/w image (320x200) stream, displaying something similar to a LED display, which is updated about once a second using AJAX. Images are pretty similar most of the time, so if I subtracted them, result would compress pretty well (even with simple RLE). Is something like this available?

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  • System of linear equations in C++?

    - by Archagon
    I need to solve a system of linear equations in my program. Is there a simple linear algebra library for C++, preferably comprised of no more than a few headers? I've been looking for nearly an hour, and all the ones I found require messing around with Linux, compiling DLLs in MinGW, etc. etc. etc. (I'm using Visual Studio 2008.)

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  • Grapher: Edit Equations Without GUI

    - by Nathan G.
    I'm trying to edit the equation of a Grapher file without opening the Grapher UI. I've gotten as far as knowing that I need a hex editor to do this. I can't, however, find my equation in that file to change it. Does anyone know how Grapher stores this information, and how to change it? My ultimate goal is to be able to change the file through the shell so I can open it and have Grapher show me my new equation (that was set with the CL). Thanks! I will set a bounty if necessary.

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  • Can I delete a differential backup from SQL Server 2005?

    - by BlueMonkMN
    I often like to create backups when testing the software I work on, and will sometimes create a differential backup if I want to be able to get back to multiple previous states. However, sometimes I realize that I forgot one thing I wanted to include in a differential backup, or I no longer need a previous differential backup. Sometimes I simply want to create a new scenario from the original base image and start working with a new series of differential backups. So I'd like to be able to delete some older differential backups so I don't get confused about which ones I'm using. But I can't find any way to delete just the differential backups, selectively or all at once.

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  • assigning in system of differential equations

    - by Alireza
    hi every one! when i solve numerically a system of two differential equations: s1:=diff(nDi, t)=...; s2:=diff(nT, t)=...; ics:={...}; #initial condition. sys := {s1, s2, ics}: sol:=dsolve(sys,numeric); with respect to "t",then the solution (for example)for "t=4" is of the form, sol(4): [t=4, n1(t)=const1, n2(t)=const2]. now, how is possible to use values of n1(t) and n2(t) for all "t"'s in another equation, namely "p", which involved n1(t) or n2(t)(like: {p=a+n1(t)*n2(t)+f(t)},where "a" and "f(t)" are defined), and to plot "p" for an interval of "t"?

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  • Orbital equations, and power required to run them

    - by Adam Davis
    Due to a discussion on the SO IRC today, I'm curious about orbital mechanics, and The equations needed to solve orbital problems The computing power required to solve complex problems The question in particular is calculating when the Earth will plow into the Sun (or vice versa, depending on the frame of reference). I suspect that all the gravitational pulls within our solar system may need to be calculated, which makes me wonder what type of computer cluster is required, or can this be done on a single box? I don't have the experience to do a back of the napkin test here, but perhaps you do? Also, much thx to Gortok for the original inspiration (see comments).

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  • Solving for the coefficent of linear equations with one known coefficent

    - by CppLearner
    clc; clear all; syms y a2 a3 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % [ 0.5 0.25 0.125 ] [ a2 ] [ y ] % [ 1 1 1 ] [ a3 ] = [ 3 ] % [ 2 4 8 ] [ 6 ] [ 2 ] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% M = [0.5 0.25 0.125; 1 1 1; 2 4 8]; t = [a2 a3 6]; r = [y 3 2]; sol = M * t' s1 = solve(sol(1), a2) % solve for a2 s2 = solve(sol(2), a3) % solve for a3 This is what I have so far. These are my output sol = conj(a2)/2 + conj(a3)/4 + 3/4 conj(a2) + conj(a3) + 6 2*conj(a2) + 4*conj(a3) + 48 s1 = - conj(a3)/2 - 3/2 - Im(a3)*i s2 = - conj(a2) - 6 - 2*Im(a2)*i sol looks like what we would have if we put them back into equation form: 0.5 * a2 + 0.25 * a3 + 0.125 * a4 a2 + a3 + a4 = 3 2*a2 + 4*a3 + 8*a4 = 2 where a4 is known == 6. My problem is, I am stuck with how to use solve to actually solve these equations to get the values of a2 and a3. s2 solve for a3 but it doesn't match what we have on paper (not quite). a2 + a3 + 6 = 3 should yield a3 = -3 - a2. because of the imaginary. Somehow I need to equate the vector solution sol to the values [y 3 2] for each row.

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