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  • Compiler optimization of repeated accessor calls

    - by apocalypse9
    I've found recently that for some types of financial calculations that the following pattern is much easier to follow and test especially in situations where we may need to get numbers from various stages of the computation. public class nonsensical_calculator { ... double _rate; int _term; int _days; double monthlyRate { get { return _rate / 12; }} public double days { get { return (1 - i); }} double ar { get { return (1+ days) /(monthlyRate * days) double bleh { get { return Math.Pow(ar - days, _term) public double raar { get { return bleh * ar/2 * ar / days; }} .... } Obviously this often results in multiple calls to the same accessor within a given formula. I was curious as to whether or not the compiler is smart enough to optimize away these repeated calls with no intervening change in state, or whether this style is causing a decent performance hit. Further reading suggestions are always appreciated

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  • Python: x-y-plot with matplotlib

    - by kame
    I want to plot some data. The first column contains the x-data. But matplotlib doesnt plot this. Where is my mistake? #fresnel formula import numpy as np from numpy import cos from scipy import * from pylab import plot, show, ylim, yticks from matplotlib import * from pprint import pprint n1 = 1.0 n2 = 1.5 #alpha, beta, intensity data = [ [10, 22, 4.3], [20, 42, 4.2], [30, 62, 3.6], [40, 83, 1.3], [45, 102, 2.8], [50, 123, 3.0], [60, 143, 3.2], [70, 163, 3.8], ] for i in range(len(data)): rhotang1 = (n1 * cos(data[i][0]) - n2 * cos(data[i][1])) rhotang2 = (n1 * cos(data[i][0]) + n2 * cos(data[i][1])) rhotang = rhotang1 / rhotang2 data[i].append(rhotang) #append 4th value pprint(data) x = data[:][0] y1 = data[:][2] y3 = data[:][3] plot(x, y1, x, y3) show() EDIT: http://paste.pocoo.org/show/205534/ But it doesnt work.

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  • How could the year 2010 be mistaken as a leap year? [closed]

    - by Templar
    According to news reports such as this one, older Playstation 3 game consoles incorrectly considered the year 2010 to be a leap year. The problem persisted through most of the Monday, March 1, which older PlayStations thought was Feb. 29, 2010, a date that doesn't exist. The standard leap year formula states that a leap year is any year that is divisible by 4, but not by 100, except if divisible by 400. The year 2010 doesn't fit any of those criteria. Any idea what programming error would have caused this?

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  • Finding zoom level from window object properties

    - by Mihai Fonoage
    Hi, I want to find out the zoom level of what is being displayed in a browser window based on the javascripts' window object properties (http://www.javascriptkit.com/jsref/window.shtml) to which I have access. I just can't seem to find the right mathematical formula for the zoom based on the inner width, page offset, etc. I found a solution, but that uses the document.body.getBoundingClientRect call which does not return anything in my case and for which I can't tell if there's a suitable replacement from the window properties. I am using Safari. Thank you, Mihai

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  • Finding the stored procedure that a Crystal Report is using

    - by Brandon
    I need to retrieve the name of the stored procedure that a crystal report is running. Is there any way to do this in C# using the CrystalDecisions.CrystalReports.Engine.ReportDocument object? I can't seem to find a property that will give me the stored procedure name. Is this even possible? I've been through almost all the properties I can think of. The DataDefinition object has collections for the Formula, Parameter, Group Name, and Running Total Fields, but not one for the Database Fields.

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  • How do I change variables from different classes?

    - by Dan T
    Before I delve into it, I'm very new to Android and I have just started learning Java last month. I've hit bumps while trying to develop my first simple app. Most of these hurdles were jumped thanks to random tutorials online. MY CODE IS VERY MESSY. Any tips are appreciated. The question above is quite broad, but this is what I want to do: It's a essentially a blood alcohol content calculator / drink keeper-tracker. Basic layout: http://i.imgur.com/JGuh7.jpg The buttons along the bottom are just regular buttons, not ImageButtons (had problems with that) Here's some example code of one: <Button android:id="@+id/Button01" android:layout_width="wrap_content" android:layout_marginRight="5dp" android:background="@drawable/addbeer"/> The buttons and TextView are all in main.xml. I have variables defined in a class called Global.java: package com.dantoth.drinkingbuddy; import android.app.Activity; public class Global extends Activity{ public static double StandardDrinks = 0; public static double BeerOunces = 12; public static double BeerPercentAlcohol = .05; public static double BeerDrink = BeerOunces * BeerPercentAlcohol; public static double BeerDrinkFinal = BeerDrink * 1.6666666; public static double ShotOunces = 1.5; public static double ShotPercentAlcohol = .4; public static double ShotDrink = ShotOunces * ShotPercentAlcohol; public static double ShotDrinkFinal = ShotDrink * 1.6666666; public static double WineOunces = 5; public static double WinePercentAlcohol = .12; public static double WineDrink = WineOunces * WinePercentAlcohol; public static double WineDrinkFinal = WineDrink * 1.6666666; public static double OtherOunces; public static double OtherPercentAlcohol; public static double OtherDrink = OtherOunces * (OtherPercentAlcohol * .01); public static double OtherDrinkFinal = OtherDrink * 1.6666666; public static double GenderConstant = 7.5; //9 for female public static double Weight = 180; public static double TimeDrinking = 60; public static double Hours = TimeDrinking / 60; public static double Bac = ((StandardDrinks / 2) * (GenderConstant / Weight)) - (0.017 * Hours); } The last variable is the important part. It calculates your BAC based on the factors involved. When I press the add beer button (Button01) I make it add 1 to StandardDrinks, simulating drinking one beer. The other variables in the Bac formula have values assigned to them in Global.java. The code that makes the beer button do stuff is in my regular class, drinkingbuddy.java: public class DrinkingBuddy extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button) findViewById(R.id.Button01); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Global.StandardDrinks = Global.StandardDrinks + Global.BeerDrinkFinal; Toast.makeText(DrinkingBuddy.this, "Mmmm... Beer", Toast.LENGTH_SHORT).show(); } }); By my perception, StandardDrinks should now have a value of 1. However, when I click the Calculate BAC button (Button05) it merely outputs the variable Bac as if StandardDrinks was still set to 0. Here is the code for the Calculate BAC button (Button05): Button button4 = (Button) findViewById(R.id.Button05); button4.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { TextView texty; texty = (TextView) findViewById(R.id.texty1); texty.setText("Your BAC is " + Global.Bac ); } }); It outputs the following to the text view: "Your BAC is -0.017". This is the Bac value for if StandardDrinks was still 0, so obviously there is some problem communicating between the classes. Can anyone help me?? The other elements of the formula (weight, time spent drinking, and the alcohol %'s and such) are variables because I will ultimately allow the user to change those values in the settings. I've heard around the water cooler that global variables are not good programming style, but this is the closest I've come to getting it to work. Any other ways of doing it are very much welcomed!

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  • Union of complex polygons

    - by grenade
    Given two polygons: POLYGON((1 0, 1 8, 6 4, 1 0)) POLYGON((4 1, 3 5, 4 9, 9 5, 4 1),(4 5, 5 7, 6 7, 4 4, 4 5)) How can I calculate the union (combined polygon)? Dave's example uses SQL server to produce the union, but I need to accomplish the same in code. I'm looking for a mathematical formula or code example in any language that exposes the actual math. I am attempting to produce maps that combine countries dynamically into regions. I asked a related question here: http://stackoverflow.com/questions/2653812/grouping-geographical-shapes

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  • Compilier optimization of repeated accessor calls C#

    - by apocalypse9
    I've found recently that for some types of financial calculations that the following pattern is much easier to follow and test especially in situations where we may need to get numbers from various stages of the computation. public class nonsensical_calculator { ... double _rate; int _term; int _days; double monthlyRate { get { return _rate / 12; }} public double days { get { return (1 - i); }} double ar { get { return (1+ days) /(monthlyRate * days) double bleh { get { return Math.Pow(ar - days, _term) public double raar { get { return bleh * ar/2 * ar / days; }} .... } Obviously this often results in multiple calls to the same accessor within a given formula. I was curious as to whether or not the compiler is smart enough to optimize away these repeated calls with no intervening change in state, or whether this style is causing a decent performance hit. Further reading suggestions are always appreciated

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  • NHibernate Criteria - How to filter on combination of properties

    - by DavGarcia
    I needed to filter a list of results using the combination of two properties. A plain SQL statement would look like this: SELECT TOP 10 * FROM Person WHERE FirstName + ' ' + LastName LIKE '%' + @Term + '%' The ICriteria in NHibernate that I ended up using was: ICriteria criteria = Session.CreateCriteria(typeof(Person)); criteria.Add(Expression.Sql( "FirstName + ' ' + LastName LIKE ?", "%" + term + "%", NHibernateUtil.String)); criteria.SetMaxResults(10); It works perfectly, but I'm not sure if it is the ideal solution since I'm still learning about NHibernate's Criteria API. What are the recommended alternatives? Is there something besides Expression.Sql that would perform the same operation? I tried Expression.Like but couldn't figure out how to combine the first and last names. Should I map a FullName property to the formula "FirstName + ' ' + LastName" in the mapping class? Should I create a read only FullName property on the domain object then map it to a column?

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  • Crystal Reports: global variable running total not displaying in header

    - by phill
    Using Crystal Reports I'm trying to display the running total of a database field in the header where all the labels are. I've attempted to do this by placing the running total (RTversion) into a formula field with the following: Shared stringvar CurrentVers; CurrentVers := {#CurrentVers}; and then in the page header section I have the following: Shared stringvar CurrentVers; EvaluateAFter({#currentVers}); CurrentVers; with {#CurrentVers} running the 1st largest number. Is this incorrect? Update: The goal is to display the latest version in the header near the labels to show what the current verseion is for comparison.

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  • How do I programmatically determine the current zoom level of a browser window?

    - by Mihai Fonoage
    Hi, I want to find out the zoom level of what is being displayed in a browser window based on the javascripts' window object properties (http://www.javascriptkit.com/jsref/window.shtml) to which I have access. I just can't seem to find the right mathematical formula for the zoom based on the inner width, page offset, etc. I found a solution, but that uses the document.body.getBoundingClientRect call which does not return anything in my case and for which I can't tell if there's a suitable replacement from the window properties. I am using Safari. Thank you, Mihai

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  • Best practices for handling math calculations in a flash project?

    - by VideoDnd
    I'm building a Flash project where it needs to handle some math, like an acceleration formula. My director has recommended a design pattern where I include the calculations directly in the flash object, but that doesn't seem like it's very good OOP. What's the best practice for calculations in Flash? Should it be a separate object, so I can keep the "non-Flash" parts together and out of the way? What are people's experiences with including it inline vs. keeping it separate?

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  • What is the difference between Multiple R-squared and Adjusted R-squared in a single-variate least s

    - by fmark
    Could someone explain to the statistically naive what the difference between Multiple R-squared and Adjusted R-squared is? I am doing a single-variate regression analysis as follows: v.lm <- lm(epm ~ n_days, data=v) print(summary(v.lm)) Results: Call: lm(formula = epm ~ n_days, data = v) Residuals: Min 1Q Median 3Q Max -693.59 -325.79 53.34 302.46 964.95 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 2550.39 92.15 27.677 <2e-16 *** n_days -13.12 5.39 -2.433 0.0216 * --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 410.1 on 28 degrees of freedom Multiple R-squared: 0.1746, Adjusted R-squared: 0.1451 F-statistic: 5.921 on 1 and 28 DF, p-value: 0.0216 Apologies for the newbiness of this question.

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  • Popularity Algorithm - SQL / Django

    - by RadiantHex
    Hi folks, I've been looking into popularity algorithms used on sites such as Reddit, Digg and even Stackoverflow. Reddit algorithm: t = (time of entry post) - (Dec 8, 2005) x = upvotes - downvotes y = {1 if x > 0, 0 if x = 0, -1 if x < 0) z = {1 if x < 0, otherwise x} log(z) + (y * t)/45000 I have always performed simple ordering within SQL, I'm wondering how I should deal with such ordering. Should it be used to define a table, or could I build an SQL with the ordering within the formula (without hindering performance)? I am also wondering, if it is possible to use multiple ordering algorithms in different occasions, without incurring into performance problems. I'm using Django and PostgreSQL. Help would be much appreciated! ^^

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  • SQL Server view: how to add missing rows using interpolation

    - by Christopher Klein
    Running into a problem. I have a table defined to hold the values of the daily treasury yield curve. It's a pretty simple table used for historical lookup of values. There are notibly some gaps in the table on year 4, 6, 8, 9, 11-19 and 21-29. The formula is pretty simple in that to calculate year 4 it's 0.5*Year3Value + 0.5*Year5Value. The problem is how can I write a VIEW that can return the missing years? I could probably do it in a stored procedure but the end result needs to be a view.

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  • What is the correct usage of blueprint-typography-body([$font-size])?

    - by Alexis Abril
    Recent convert to RoR and I've been using Compass w/ Blueprint to dip into the proverbial pool. Compass has been fantastic, but I've come across something strange within the Typography library. The blueprint-typography-body mixin contains the following: =blueprint-typography-body($font-size: $blueprint-font-size) line-height: 1.5 +normal-text font-size: 100% * $font-size / 16px My question revolves around "font-size." I'm a bit lost, as I would expect to pass in a font size and have that size reflected upon page load. However, in this scenario the formula seems to dictate a percentage against the default font. ie: +blueprint-typography-body(10px) //produces 7.5px off of the default font size of 12px from what I can tell. In essence, I'm curious if there is a standard to setting font size within Compass other than explicitly declaring "font-size: 10px". Note: The reason I'm leaning towards Blueprint/Compass font stylings is due to the standardization of line-heights, fonts and colors.

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  • What is the correct way to specify dimensions in DIP from Java code ?

    - by Pavel Lahoda
    Trying to digest docs about design Multiple resolutions (http://d.android.com/guide/practices/screens_support.html#dips-pels) I found that it is possible to set dimensions of my interface elements in XML layouts using DIPs as in following fragment : "android:layout_width="10dip" But all Java interface takes integer as arguments and there is no way to specify dimensions in DIPs. What is the correct way to calculate this ? I figured that I have to use property density of DisplayMetrics class but is this a correct way ? May I relly that formula : pixels * DisplayMetrics.density = dip is always correct ? Will there be API in DIPs for Java ?

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  • Hex web colours

    - by Mick
    Hi I am displaying a colour as a hex value in php . Is it possible to vary the shade of colour by subtracting a number from the hex value ? What I want to do it display vivid web safe colour but if selected I want to dull or lighten the colour. I know I can just use two shades of colour but I could hundred of potential colours . to be clear #66cc00 is bright green and #99ffcc is a very pale green . What do i subtract to get the second colour ? is there any formula because I just can get it . Thanks for any help Cheers

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  • Finding coordinates of a point between two points?

    - by Nicros
    Doing some 3D stuff in wpf- want to use a simpler test to see if everything is working (before moving to curves). The basic question is given two points x1,y1,z1 and x2,y2,z2 I have calculated the distance between the points. But how to find the coordinates of another point (x3,y3,z3) that lies on that line at some distance? I.e. if my line is 100 long between -50,0,0 and 50,0,0 what are the coordinates of the point at 100 * 0.1 along the line? I think this is a simple formula but I haven't found it yet....

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  • When is JavaScript's eval() not evil?

    - by Richard Turner
    I'm writing some JavaScript to parse user-entered functions (for spreadsheet-like functionality). Having parsed the formula I could convert it into JavaScript and run eval() on it to yield the result. However, I've always shied away from using eval() if I can avoid it because it's evil (and, rightly or wrongly, I've always thought it is even more evil in JavaScript because the code to be evaluated might be changed by the user). Obviously one has to use eval() to parse JSON (I presume that JS libraries use eval() for this somewhere, even if they run the JSON through a regex check first), but when else, other than when manipulating JSON, it is OK to use eval()?

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  • Estimate gaussian (mixture) density from a set of weighted samples

    - by Christian
    Assume I have a set of weighted samples, where each samples has a corresponding weight between 0 and 1. I'd like to estimate the parameters of a gaussian mixture distribution that is biased towards the samples with higher weight. In the usual non-weighted case gaussian mixture estimation is done via the EM algorithm. Does anyone know an implementation (any language is ok) that permits passing weights? If not, does anyone know how to modify the algorithm to account for the weights? If not, can some one give me a hint on how to incorporate the weights in the initial formula of the maximum-log-likelihood formulation of the problem? Thanks!

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  • draw an arc given 3 points in SWT

    - by Ahmed Kotb
    iam using the swt java library and iam having a problem. the gc draw arc method takes the following arguments GC.drawArc(int x, int y, int width, int height, int startAngle, int endAngle); but i want to be able to draw the arc using 3 arguments : the source ,destination and control points. is there any formula to convert between those parameters ? QuadCurve2D class do exactly what i want but it is not AWT not swt ...and i tried to use java2d under swt but it was very slow .... any solutions ?

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  • crystal reporting in vs2008

    - by hatem gamil
    hi all i wana ask a question about crystal reporting in vs 2008 lets say i have a report with these data customer_ID Customer_Name Order_amoont Order_Date (#group1 VipCustomer) 1 xyz 3 1/1/2010 2 abc 4 2/2/2010 5 sds 21 3/12/2009 (#Group2 NormalCustomer) 3 tyt 2 3/3/2010 4 ha 4 21/3/2009 i want only to display records where Order_Date year is in 2010 only so i went to the section expert and i added a condintion in suppress formula Year(order_Date)=2010 and i get the result ,,the question is how to count how many vip customers ordered in 2010 only and how many normal customer order in 2010 only ,,then i want the total number of both type of customers to be displayed to have a report like that:: customer_ID Customer_Name Order_amoont Order_Date (#group1 VipCustomer) 1 xyz 3 1/1/2010 2 abc 4 2/2/2010 subtotal 2 (#Group2 NormalCustomer) 3 tyt 2 3/3/2010 subtotal 1 total 3 thnx

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  • Render only the segment/area of a circle that intersects the main circle

    - by Greenhouse Gases
    I absolutely love maths (or 'math' as most of you would say!) but I haven't done it to a level where I know the answer to this problem. I have a main circle which could have a centre point at any x and y on a display. Other circles will move around the display at will but at any given call to a render method I want to render not only those circles that intersect the main circle, but also only render the segment of that circle that is visible inside the main circle. An analogy would be a shadow cast on a real life object, and I only want to draw the part of that object that is 'illuminated'. I want to do this preferably in Java, but if you have a raw formula that would be appreciated. I wonder how one might draw the shape and fill it in Java, I'm sure there must be some variation on a polyline with arcs or something? Many thanks

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  • counting fields based on group in crystal report

    - by hatem gamil
    hi all i wana ask a question about crystal reporting in vs 2008 lets say i have a report with these data customer_ID Customer_Name Order_amoont Order_Date (#group1 VipCustomer) 1 xyz 3 1/1/2010 2 abc 4 2/2/2010 5 sds 21 3/12/2009 (#Group2 NormalCustomer) 3 tyt 2 3/3/2010 4 ha 4 21/3/2009 i want only to display records where Order_Date year is in 2010 only so i went to the section expert and i added a condintion in suppress formula Year(order_Date)=2010 and i get the result ,,the question is how to count how many vip customers ordered in 2010 only and how many normal customer order in 2010 only ,,then i want the total number of both type of customers to be displayed to have a report like that:: customer_ID Customer_Name Order_amoont Order_Date (#group1 VipCustomer) 1 xyz 3 1/1/2010 2 abc 4 2/2/2010 subtotal 2 (#Group2 NormalCustomer) 3 tyt 2 3/3/2010 subtotal 1 total 3 thnx

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