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  • double accepts_nested_attributes_for

    - by sfusion
    does anyone know if it is possible to do a double nested form for. so that i could upload images to a set from an article form. e.g. Article has_many :image_sets ImageSet belongs_to :article has_many :images Image belongs_to :image_set

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  • Implications of trying to double free memory space in C

    - by SidNoob
    Here' my piece of code: #include <stdio.h> #include<stdlib.h> struct student{ char *name; }; int main() { struct student s; s.name = malloc(sizeof(char *)); // I hope this is the right way... printf("Name: "); scanf("%[^\n]", s.name); printf("You Entered: \n\n"); printf("%s\n", s.name); free(s.name); // This will cause my code to break } All I know is that dynamic allocation on the 'heap' needs to be freed. My question is, when I run the program, sometimes the code runs successfully. i.e. ./struct Name: Thisis Myname You Entered: Thisis Myname I tried reading this I've concluded that I'm trying to double-free a piece of memory i.e. I'm trying to free a piece of memory that is already free? (hope I'm correct here. If Yes, what could be the Security Implications of a double-free?) While it fails sometimes as its supposed to: ./struct Name: CrazyFishMotorhead Rider You Entered: CrazyFishMotorhead Rider *** glibc detected *** ./struct: free(): invalid next size (fast): 0x08adb008 *** ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6(+0x6b161)[0xb7612161] /lib/tls/i686/cmov/libc.so.6(+0x6c9b8)[0xb76139b8] /lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0xb7616a9d] ./struct[0x8048533] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0xb75bdbd6] ./struct[0x8048441] ======= Memory map: ======== 08048000-08049000 r-xp 00000000 08:01 288098 /root/struct 08049000-0804a000 r--p 00000000 08:01 288098 /root/struct 0804a000-0804b000 rw-p 00001000 08:01 288098 /root/struct 08adb000-08afc000 rw-p 00000000 00:00 0 [heap] b7400000-b7421000 rw-p 00000000 00:00 0 b7421000-b7500000 ---p 00000000 00:00 0 b7575000-b7592000 r-xp 00000000 08:01 788956 /lib/libgcc_s.so.1 b7592000-b7593000 r--p 0001c000 08:01 788956 /lib/libgcc_s.so.1 b7593000-b7594000 rw-p 0001d000 08:01 788956 /lib/libgcc_s.so.1 b75a6000-b75a7000 rw-p 00000000 00:00 0 b75a7000-b76fa000 r-xp 00000000 08:01 920678 /lib/tls/i686/cmov/libc-2.11.1.so b76fa000-b76fc000 r--p 00153000 08:01 920678 /lib/tls/i686/cmov/libc-2.11.1.so b76fc000-b76fd000 rw-p 00155000 08:01 920678 /lib/tls/i686/cmov/libc-2.11.1.so b76fd000-b7700000 rw-p 00000000 00:00 0 b7710000-b7714000 rw-p 00000000 00:00 0 b7714000-b7715000 r-xp 00000000 00:00 0 [vdso] b7715000-b7730000 r-xp 00000000 08:01 788898 /lib/ld-2.11.1.so b7730000-b7731000 r--p 0001a000 08:01 788898 /lib/ld-2.11.1.so b7731000-b7732000 rw-p 0001b000 08:01 788898 /lib/ld-2.11.1.so bffd5000-bfff6000 rw-p 00000000 00:00 0 [stack] Aborted So why is it that my code does work sometimes? i.e. the compiler is not able to detect at times that I'm trying to free an already freed memory. Has it got to do something with my stack/heap size?

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  • convert string to double

    - by James123
    I have string value in that I need to convert to double in VB.Net. Conditions are like below string = "12345.00232232" if condition is 3 (2 digits after decimal and comma) display = 12,345.00 if condition is 5 (5 digits after decimal and comma) display = 12,345.00232 If Condition is 7 ( 5 digits after decimal and no comma) display = 12345.00232 How can I do that in VB.Net?

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  • select multiple double side

    - by Mercer
    hello, i want to do a select multiple double side like this : http://www.senamion.com/blog/jmultiselect2side.html (Demo2) but i don't know how i can retrieve my data when i click submit button..?

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  • .htaccess double redirect of a 404 page.

    - by peti
    Hi, my custom 404.php page is located in /includes/404.php. My current .htaccess file does the following redirect: ErrorDocument 404 http://imgpls.localhost/includes/404.php So the url looks like: mysite.com/includes/404.php . Basically I need a double redirect: 1) 404 eror page to mysite.com/404.php (so the url looks nice) 2) mysite.com/404.php to mysite.com/includes/404.php where the file actually is. How can I achieve that? Thanks in advance.

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  • Limit a double to two decimal places

    - by Jacob
    How do I achieve the following conversion from double to a string: 1.4324 => "1.43" 9.4000 => "9.4" 43.000 => "43" ie I want to round to to decimal places but dont want any trailing zeros, ie i dont want 9.4 => "9.40" (wrong) 43.000 => "43.00" (wrong) So this code which I have now doesn't work as it displays excess twos: [NSString stringWithFormat: @"%.2f", total]

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  • Makefile patsubs double replacement

    - by aaa
    hello. is a possible to do something like this, without shell command: CXX_MODULES += $(patsubst %, %/%.cpp, $(LIBRARIES)) notice double replacement which does not work (only first replacement happens) after some tinkering I came up with $(join $(LIBRARIES), $(patsubst %, /%.cpp, $(LIBRARIES))) Thank you

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  • double click and select the path(including '/') in Terminal.app

    - by mash
    I'm using Terminal.app on Mac OS10.6.3, with gnu screen and zsh. What I want to do is, see pwd(or an URL) in Terminal.app and double click on it, and select the whole path, to copy and paste after that. But what I get now is a single directory name, because '/' is not treated as a word. I found that iTerm has a setting to change it(iTerm - Preferences - Mouse - Characters considered part of a word), but is there any way to do this on my environment?

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  • JS regular expression to find a substring surrounded by double quotes

    - by 2619
    I need to find a substring surrounded by double quotes, for example, like "test", "te\"st" or "", but not """ neither "\". To achieve this, which is the best way to go for it in the following 1) /".*"/g 2) /"[^"\\]*(?:\\[\S\s][^"\\]*)*"/g 3) /"(?:\\?[\S\s])*?"/g 4) /"([^"\\]*("|\\[\S\s]))+/g I was asked this question yesterday during an interview, and would like to know the answer for future reference.

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  • using PixelBender to double the size of a bitmap

    - by jedierikb
    I have a performance question about pixel bender. I want to enlarge many BitmapData (double their size into new BitmapData). I was doing this with as3, but wanted to use pixel bender to get better performance. On my machines, I get great comparative performance out of many pixel bender demonstrations. To my surprise (or bad coding / understanding), I am getting much worse performance out of pixel bender -- 2 seconds to do 3000 scalings vs .5 seconds! I expected to get at least the same performance as as3. What am I doing wrong? I got the straightforward pixel bender code here (and it is included below for easy reference). package { import aCore.aUtil.timingUtils; import flash.display.BitmapData; import flash.display.Shader; import flash.display.ShaderJob; import flash.display.Sprite; import flash.display.StageAlign; import flash.display.StageScaleMode; import flash.events.Event; import flash.geom.Matrix; public class flashFlash extends Sprite { [Embed ( source="pixelbender/bilinearresample.pbj", mimeType="application/octet-stream" ) ] private static var BilinearScaling:Class; public function flashFlash( ):void { stage.align = StageAlign.TOP_LEFT; stage.scaleMode = StageScaleMode.NO_SCALE; addEventListener( Event.ENTER_FRAME, efCb, false, 0, true ); } private function efCb( evt:Event ):void { removeEventListener( Event.ENTER_FRAME, efCb, false ); traceTime( "init" ); var srcBmd:BitmapData = new BitmapData( 80, 120, false, 0 ); var destBmd:BitmapData = new BitmapData( 160, 240, false, 0 ); var mx:Matrix = new Matrix( ); mx.scale( 2, 2 ); for (var i:uint = 0; i < 3000; i++) { destBmd.draw( srcBmd, mx ); } traceTime( "scaled with as3" ); // create and configure a Shader object var shader:Shader = new Shader( ); shader.byteCode = new BilinearScaling( ); shader.data.scale.value = [2]; shader.data.src.input = srcBmd; for (var j:uint = 0; j < 3000; j++) { var shaderJob:ShaderJob = new ShaderJob( ); shaderJob.shader = shader; shaderJob.target = destBmd; shaderJob.start( true ); } traceTime( "scaled with pixel bender bilinearresample.pbj" ); } private static var _lastTraceTime:Number = new Date().getTime(); public static function traceTime( note:String ):Number { var nowTime:Number = new Date().getTime(); var diff:Number = (nowTime-_lastTraceTime); trace( "[t" + diff + "] " + note ); _lastTraceTime = nowTime; return diff; } } } And the pixel bender code: <languageVersion : 1.0;> kernel BilinearResample < namespace : "com.brooksandrus.pixelbender"; vendor : "Brooks Andrus"; version : 1; description : "Resizes an image using bilinear resampling. Constrains aspect ratio - divide Math.max( input.width / output.width, input.height / output.height ) and pass in to the scale parameter"; > { parameter float scale < minValue: 0.0; maxValue: 1000.0; defaultValue: 1.0; >; input image4 src; output pixel4 dst; void evaluatePixel() { // scale should be Math.max( src.width / output.width, src.height / output.height ) dst = sampleLinear( src, outCoord() * scale ); // bilinear scaling } }

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  • Optimizing sparse dot-product in C#

    - by Haggai
    Hello. I'm trying to calculate the dot-product of two very sparse associative arrays. The arrays contain an ID and a value, so the calculation should be done only on those IDs that are common to both arrays, e.g. <(1, 0.5), (3, 0.7), (12, 1.3) * <(2, 0.4), (3, 2.3), (12, 4.7) = 0.7*2.3 + 1.3*4.7 . My implementation (call it dict) currently uses Dictionaries, but it is too slow to my taste. double dot_product(IDictionary<int, double> arr1, IDictionary<int, double> arr2) { double res = 0; double val2; foreach (KeyValuePair<int, double> p in arr1) if (arr2.TryGetValue(p.Key, out val2)) res += p.Value * val2; return res; } The full arrays have about 500,000 entries each, while the sparse ones are only tens to hundreds entries each. I did some experiments with toy versions of dot products. First I tried to multiply just two double arrays to see the ultimate speed I can get (let's call this "flat"). Then I tried to change the implementation of the associative array multiplication using an int[] ID array and a double[] values array, walking together on both ID arrays and multiplying when they are equal (let's call this "double"). I then tried to run all three versions with debug or release, with F5 or Ctrl-F5. The results are as follows: debug F5: dict: 5.29s double: 4.18s (79% of dict) flat: 0.99s (19% of dict, 24% of double) debug ^F5: dict: 5.23s double: 4.19s (80% of dict) flat: 0.98s (19% of dict, 23% of double) release F5: dict: 5.29s double: 3.08s (58% of dict) flat: 0.81s (15% of dict, 26% of double) release ^F5: dict: 4.62s double: 1.22s (26% of dict) flat: 0.29s ( 6% of dict, 24% of double) I don't understand these results. Why isn't the dictionary version optimized in release F5 as do the double and flat versions? Why is it only slightly optimized in the release ^F5 version while the other two are heavily optimized? Also, since converting my code into the "double" scheme would mean lots of work - do you have any suggestions how to optimize the dictionary one? Thanks! Haggai

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  • Calling compiled C from R with .C()

    - by Sarah
    I'm trying to call a program (function getNBDensities in the C executable measurementDensities_out) from R. The function is passed several arrays and the variable double runsum. Right now, the getNBDensities function basically does nothing: it prints to screen the values of passed parameters. My problem is the syntax of calling the function: array(.C("getNBDensities", hr = as.double(hosp.rate), # a vector (s x 1) sp = as.double(samplingProbabilities), # another vector (s x 1) odh = as.double(odh), # another vector (s x 1) simCases = as.integer(x[c("xC1","xC2","xC3")]), # another vector (s x 1) obsCases = as.integer(y[c("yC1","yC2","yC3")]), # another vector (s x 1) runsum = as.double(runsum), # double DUP = TRUE, NAOK = TRUE, PACKAGE = "measurementDensities_out")$f, dim = length(y[c("yC1","yC2","yC3")]), dimnames = c("yC1","yC2","yC3")) The error I get, after proper execution of the function (i.e., the right output is printed to screen), is Error in dim(data) <- dim : attempt to set an attribute on NULL I'm unclear what the dimensions are that I should be passing the function: should it be s x 5 + 1 (five vectors of length s and one double)? I've tried all sorts of combinations (including sx5+1) and have found only seemingly conflicting descriptions/examples online of what's supposed to happen here. For those who are interested, the C code is below: #include <R.h> #include <Rmath.h> #include <math.h> #include <Rdefines.h> #include <R_ext/PrtUtil.h> #define NUM_STRAINS 3 #define DEBUG void getNBDensities( double *hr, double *sp, double *odh, int *simCases, int *obsCases, double *runsum ); void getNBDensities( double *hr, double *sp, double *odh, int *simCases, int *obsCases, double *runsum ) { #ifdef DEBUG for ( int s = 0; s < NUM_STRAINS; s++ ) { Rprintf("\nFor strain %d",s); Rprintf("\n\tHospitalization rate = %lg", hr[s]); Rprintf("\n\tSimulation probability = %lg",sp[s]); Rprintf("\n\tSimulated cases = %d",simCases[s]); Rprintf("\n\tObserved cases = %d",obsCases[s]); Rprintf("\n\tOverdispersion parameter = %lg",odh[s]); } Rprintf("\nRunning sum = %lg",runsum[0]); #endif } naive solution While better (i.e., potentially faster or syntactically clearer) solutions may exist (see Dirk's answer below), the following simplification of the code works: out<-.C("getNBDensities", hr = as.double(hosp.rate), sp = as.double(samplingProbabilities), odh = as.double(odh), simCases = as.integer(x[c("xC1","xC2","xC3")]), obsCases = as.integer(y[c("yC1","yC2","yC3")]), runsum = as.double(runsum)) The variables can be accessed in >out.

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