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• directx 9 hlsl vs. directx 10 hlsl : syntex the same.

  - by numerical25

  For the past month or so I been busting my behind trying to learn directx. So I been mixing back back and fourth from directx 9 to directx 10. One of the major changes I've seen in the two is how to process vectors in the graphics card. one of the drastic changes I notice is how you get the gpu to recognize your structs. In directx 9 you define the Flexible Vertex Formats your typical set up would be like this... #define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE) in directx 10 I believe the equivalent is the input vertex description D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0} }; I notice in directx 10. it is more descriptive. besides this, what are some of the drastic changes made. and is the hlsl syntax the same for both.

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• Find the closest vector

  - by Alexey Lebedev

  Hello! Recently I wrote the algorithm to quantize an RGB image. Every pixel is represented by an (R,G,B) vector, and quantization codebook is a couple of 3-dimensional vectors. Every pixel of the image needs to be mapped to (say, "replaced by") the codebook pixel closest in terms of euclidean distance (more exactly, squared euclidean). I did it as follows: class EuclideanMetric(DistanceMetric): def __call__(self, x, y): d = x - y return sqrt(sum(d * d, -1)) class Quantizer(object): def __init__(self, codebook, distanceMetric = EuclideanMetric()): self._codebook = codebook self._distMetric = distanceMetric def quantize(self, imageArray): quantizedRaster = zeros(imageArray.shape) X = quantizedRaster.shape[0] Y = quantizedRaster.shape[1] for i in xrange(0, X): print i for j in xrange(0, Y): dist = self._distMetric(imageArray[i,j], self._codebook) code = argmin(dist) quantizedRaster[i,j] = self._codebook[code] return quantizedRaster ...and it works awfully, almost 800 seconds on my Pentium Core Duo 2.2 GHz, 4 Gigs of memory and an image of 2600*2700 pixels:( Is there a way to somewhat optimize this? Maybe the other algorithm or some Python-specific optimizations.

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• An algorithm Problem

  - by Vignesh

  For coverage, I've a set of run time variables of from my program execution. It happens that I get it from a series of executions(Automated testing). ie. its a vector<vector<var,value>> I've a limited set of variables with expected values and generate combination s, that is I have vector<vector<var,value>(smaller than the execution vector)>. Now I need to compare and tell which of the combination I generated were exactly executed in one of the tests. My algo is O(n^4). Is there any way to bring it down. Something like set intersection. I'm using java, and vectors because of thread safety.

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• DirectX 9 HLSL vs. DirectX 10 HLSL: syntax the same?

  - by numerical25

  For the past month or so, I have been busting my behind trying to learn DirectX. So I've been mixing back back and forth between DirectX 9 and 10. One of the major changes I've seen in the two is how to process vectors in the graphics card. One of the drastic changes I notice is how you get the GPU to recognize your structs. In DirectX 9, you define the Flexible Vertex Formats. Your typical set up would be like this: #define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE) In DirectX 10, I believe the equivalent is the input vertex description: D3D10_INPUT_ELEMENT_DESC layout[] = { {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0}, {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0} }; I notice in DirectX 10 that it is more descriptive. Besides this, what are some of the drastic changes made, and is the HLSL syntax the same for both?

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• C++ - dynamic pointer of array

  - by Eagle

  Hi to all, first i would like to say i am Newbie in C++. As part of my master thesis i am writing a program in C++ which also get as parameters the variables m and d (both integers). Were d is the power of 2 (this means 2^d elements). Parameter m define the number of possible interactions between one element and the total group (2^d elements). The number of possible interactions is computed as following: \kappa = \sum_{i=0}^m\binom{d}{i} (at present i generate vector of vectors for 2^d x \kappa, but my Prof. would like me to create different statistics to different m's. My first though was to to generate a dynamic array of m arrays of different sizes... Then i though of defining a 3-dim array with the biggest needed 2d array, but also program speed is important (e.g d = 20). i would like to ask for your advice how to define such kind of dynamic array that will also be fast. Regards

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• Clojure: seq (cons) vs. list (conj)

  - by dbyrne

  I know that cons returns a seq and conj returns a collection. I also know that conj "adds" the item to the optimal end of the collection, and cons always "adds" the item to the front. This example illustrates both of these points: user=> (conj [1 2 3] 4) //returns a collection [1 2 3 4] user=> (cons 4 [1 2 3]) //returns a seq (4 1 2 3) For vectors, maps, and sets these differences make sense to me. However, for lists they seem identical. user=> (conj '(3 2 1) 4) (4 3 2 1) user=> (cons 4 '(3 2 1)) (4 3 2 1) Are there any examples using lists where conj vs. cons exhibit different behaviors, or are they truly interchangeable? Phrased differently, is there an example where a list and a seq cannot be used equivalently?

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• Historical security flaws of popular PHP CMS's?

  - by VirtuosiMedia

  I'm creating a PHP CMS, one that I hope will be used by the public. Security is a major concern and I'd like to learn from some of the popular PHP CMS's like Wordpress, Joomla, Drupal, etc. What are some security flaws or vulnerabilities that they have they had in the past that I can avoid in my application and what strategies can I use to avoid them? What are other issues that I need to be concerned with that they perhaps didn't face as a vulnerability because they handled it correctly from the start? What additional security features or measures would you include? Please be as specific as possible. I'm generally aware of most of the usual attack vectors, but I want to make sure that all the bases are covered, so don't be afraid to mention the obvious as well. Assume PHP 5.2+.

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• Difference between BOOST_CHECK_CLOSE and BOOST_CHECK_CLOSE_FRACTION?

  - by Rhys Ulerich

  Can anyone describe the difference in behavior between BOOST_CHECK_CLOSE and BOOST_CHECK_CLOSE_FRACTION? The documentation implies the that both macros treat their third parameter identically, which makes me suspect the documentation is wrong. In particular, BOOST_CHECK_CLOSE_FRACTION gives me some odd looking results: error in "...": difference between *expected{0} and *actual{-1.7763568394002506e-16} exceeds 9.9999999999999995e-07 Is there a gotcha because I expect a zero result? I've not been successful at reading through the underlying macro declarations. Please note BOOST_CHECK_SMALL isn't appropriate for my use case (comparing two vectors after a linear algebra operation).

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• Is there a decent vector / spline library for php?

  - by Brendan Heywood

  Does anyone know of the best way to render clean vectors into a php image and then serve it as a jpeg/png? Specifically I want to draw lines, polygons and splines which are anti-aliased and then serve them up as jpegs. Preferably also with an alpha option when rendering. What would be spectacular is a php library with a similar API to Raphael (without the animation) - not only because Raphael has a great API but also because I'm already using it on my website for the dynamic bits but also need to bake jpeg's in parallel for static consumption.

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• Replacing a colour/colours in a movieclip with different colours?

  - by Oli

  I am trying to take a movieclip of a character and change the colour of their clothes. The character is comprised of vectors. So far I have semi-sucessfully used this method: stop the movieclip take the bitmap data from the current frame use threshold to replace the colour store the resulting bitmap data in an array add an onenterframe function - clear the current frame and add the bitmap data from the processed data in the array So - this works pretty well. Each frame is only processed once at the beginning and then the write to the movieclip is very quick. However! As the replacement is being performed on a bitmap there is an amount of aliasing that takes place to remove jaggies/pixelation. This produces colours that are not matched using threshold. So the main colour is replaced correctly but it is surrounded by a halo of mixed colours :( I am sure there should be a better way to do this. Any ideas or answers would be greatly apreciated - Thanks.

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• What explains the term orthogonal in a more non-nerd fashion?

  - by dontWatchMyProfile

  For example: Cardinality and optionality are orthogonal properties of a relationship. You can specify that a relationship is optional, even if you have specified upper and/or lower bounds. This means that there do not have to be any objects at the destination, but if there are then the number of objects must lie within the bounds specified. What exactly does "orthogonal" mean? I bet it's just a fancy soundig nerd-style word for something that could be expressed a lot easier to understand for average people ;) From wikipedia: In mathematics, two vectors are orthogonal if they are perpendicular, i.e., they form a right angle. The word comes from the Greek ????? (orthos), meaning "straight", and ????a (gonia), meaning "angle". Anyone?

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• Disabling javascript in specific block/div (containing suspect HTML) ?

  - by T4NK3R

  Is it, in any way, possible to disable the browsers execution of script inside a block/section/element ? My scenario is, that I'm letting my (future) users create "rich content" (using CK-editor). Content that wil later be shown to other users - with all the dangers that imply: xss, redirection, identity theft, spam and what not... I've, more or less, given up on trying to "sanitize" the incomming XHTML, after seeing how many known "vectors of attack" there are: http://ha.ckers.org/xss.html What I'm really looking for is something like: < div id="userContent"< scriptOFF suspect HTML < /scriptOFF< /div

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• Last Observation Carried Forward In a data frame?

  - by Tal Galili

  Hi all, I wish to implement a "Last Observation Carried Forward" for a data set I am working on which has missing values at the end of it. Here is a simple code to do it (question after it): LOCF <- function(x) { # Last Observation Carried Forward (for a left to right series) LOCF <- max(which(!is.na(x))) # the location of the Last Observation to Carry Forward x[LOCF:length(x)] <- x[LOCF] return(x) } # example: LOCF(c(1,2,3,4,NA,NA)) LOCF(c(1,NA,3,4,NA,NA)) Now this works great for simple vectors. But if I where to try and use it on a data frame: a <- data.frame(rep("a",4), 1:4,1:4, c(1,NA,NA,NA)) a t(apply(a, 1, LOCF)) # will make a mess It will turn my data frame into a character matrix. Can you think of a way to do LOCF on a data.frame, without turning it into a matrix? (I could use loops and such to correct the mess, but would love for a more elegant solution) Cheers, Tal

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• MATLAB: draw centroids

  - by Myx

  Hello - my main question is given a feature centroid, how can I draw it in MATLAB? In more detail, I have an NxNx3 image (an rgb image) of which I take 4x4 blocks and compute a 6-dimensional feature vector for each block. I store these feature vectors in an Mx6 matrix on which I run kmeans function and obtain the centroids in a kx6 matrix, where k is the number of clusters and 6 is the number of features for each block. How can I draw these center clusters in my image in order to visualize if the algorithm is performing the way I wish it to perform? Or if anyone has any other way/suggestions on how I can visualize the centroids on my image, I'd greatly appreciate it. Thank you.

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• Rewriting a simple Pygame 2D drawing function in C++

  - by Dominic Bou-Samra

  I have a 2D list of vectors (say 20x20 / 400 points) and I am drawing these points on a screen like so: for row in grid: for point in row: pygame.draw.circle(window, white, (particle.x, particle.y), 2, 0) pygame.display.flip() #redraw the screen This works perfectly, however it's much slower then I expected. I want to rewrite this in C++ and hopefully learn some stuff (I am doing a unit on C++ atm, so it'll help) on the way. What's the easiest way to approach this? I have looked at Direct X, and have so far followed a bunch of tutorials and have drawn some rudimentary triangles. However I can't find a simple (draw point).

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• STL member variable initalization issue with windows API

  - by Django

  I am creating a windows app that uses a vector of stings as a member variable. For some reason, I can compile but when it tries to get at any of the vectors members is crashes. the error is 0xC0000005: Access violation reading location 0xcdcdcdd9. in the member function of the vector class. this is the size() function where it breaks. size_type capacity() const { // return current length of allocated storage return (this->_Myend - this->_Myfirst); } I am using visual studios 2010. thank you Django

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• Cuda program results are always zero in HW, correct in EMU??

  - by Orion Nebula

  Hi all! I am having a weird problem .. I have written a CUDA code which executes correctly in emulation and all results show up.. however, when executed on hardware "G210" .. the results in the result memory are always 0 I am passing two vectors to the kernel, one with random variables the other is initialized to zero, the code copies the first vector to shared memory, does some swapping and other operations and then writes back the results on the second vector (the one with the initial 0's) I am using double precision, the -arch sm13 flag is used, all memory allocation also use sizeof(double) .. I have checked if the kernel is invoked, it does .. so no problems here .. the cudaMemCpy has no problems .. what could be the problem .. :( why would it work in emulation but not on HW I am quite confused .. any ideas?

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• Type parameterization in Scala

  - by horatius83

  So I'm learning Scala at the moment, and I'm trying to create an abstract vector class with a vector-space of 3 (x,y,z coordinates). I'm trying to add two of these vectors together with the following code: package math class Vector3[T](ax:T,ay:T,az:T) { def x = ax def y = ay def z = az override def toString = "<"+x+", "+y+", "+z+">" def add(that: Vector3[T]) = new Vector3(x+that.x, y+that.y, z+that.z) } The problem is I keep getting this error: error: type mismatch; found : T required: String def add(that: Vector3[T]) = new Vector3(x+that.x, y+that.y, z+that.z) I've tried commenting out the "toString" method above, but that doesn't seem to have any effect. Can anyone tell me what I'm doing wrong?

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• Inheritance vs specific types in Financial Modelling for cashflows

  - by BlueTrin

  Hello, I have to program some financial applications where I have to represent a schedule of flows. The flows can be of 3 types: - fee flow (just a lump payment at some date) - floating rate flow (the flow is dependant of an interest rate to be determined at a later date) - fixed rate flow (the flow is dependant of an interest rate determined when the deal is done) I need to keep the whole information and I need to represent a schedule of these flows. Originally I wanted to use inheritance and create three classes FeeFlow, FloatingFlow, FixedFlow all inheriting from ICashFlow and implement some method GetFlowType() returning an enum then I could dynamic_cast the object to the correct type. That would allow me to have only one vector to represent my schedule. What do you think of this design, should I rather use three vectors vector, vector and vector to avoid the dynamic casts ?

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• MATLAB: Need to make a 4D plot (3D + Colour/Color)

  - by user1305624

  I need to make a 3D surface where colour will represent the fourth variable. I know "surf" is SIMILAR to what I need, but that's not quite it. Basically, I have the following variables: t = [1:m] y = [1:n] a = [1:o] These should be the three Cartesian corodinate axes. I also have a variable S that is of dimensions m x n x o, and is basically the amplitude, a function of the previous three variables (i.e. S = f(t,y,a)). I want this to be represented by colour. So to summarize, I need a graph of the form (t,y,a,S), where the first three variables are vectors of unequal sizes and the final variable is a multidimensional array whose dimensions are determined by the first three. Thanks in advance.

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• What is the need for normalizing a vector?

  - by Rashed Hassan

  Trying to understand vectors a bit more. What is the need for normalizing a vector? If I have a vector, N = (x, y, z) What do you actually get when you normalize it - I get the idea you have to divide x/|N| y/|N| & z/|N|. My question is, why do we do this thing, I mean what do we get out of this equation? What is the meaning or 'inside' purpose of doing this. A bit of a maths question, I apologize, but I am really not clear in this topic.

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• Grammatically correct double-noun identifiers, plural versions

  - by Michal Czardybon

  Consider compounds of two nouns, which in natural English would most often appear in the form "noun of noun", e.g. "direction of light", "output of a filter". When programming we usually write "LightDirection" and "FilterOutput". Now, I have a problem with plural nouns. There are two cases: 1) singular of plural e.g. "union of (two) sets", "intersection of (two) segments" Which is correct, SetUnion and SegmentIntersection or SetsUnion and SegmentsIntersection? 2) plural of plural There are two subcases: (a) Many elements, each having many related elements, e.g. "outputs of filters" (b) Many elements, each having single related element, e.g. "directions of vectors" Shell I use FilterOutputs and VectorDirections or FiltersOutputs and VectorsDirections? I suspect correct is the first version (FilterOutupts, VectorDirections), but I think it may lead to ambiguities, e.g. FilterOutputs - many outputs of a single filter or many outputs of many filters? LineSegmentProjections - projections of many segments or many projections of a single segment?

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• Better way of enforcing this template?

  - by Dennis Ritchie

  Currently, I have a function template like this that converts a vector into a string (just a natural string, separating the elements with a comma): //the type T must be passable into std::to_string template<typename T> std::string vec_to_str(const std::vector<T> &vec); As you can see, this is only meant for vectors whose elements can be passed into the built-in std::to_string function (such as int, double, etc.) Is it considered a good practice to document with comments the allowed T? If not, what should I do? Is it possible to enforce this in a better way?

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• Generating a random displacement on the unit sphere

  - by becko

  Given a unit vector n, I need to generate, as fast as possible, another random unit vector m. The deviation of m from n should be on the order of a positive parameter sigma, and the distribution of m on the unit sphere should be symmetrical around n. I have no specific requirements on the representation of unit vectors, so you can use spherical angles, Cartesian coordinates, or whatever turns out to be convenient. Also, there are no precise requirements on the probability distributions used, as long as it decays when m deviates more than sigma from n. I am working with gsl and C. I have come up with a somewhat convoluted method using Cartesian coordinates. I will post it later if it is useful, but I would like to see people's ideas.

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• How do I resize a flat vector icon so that it preserves hard edges in Photoshop (CS4)

  - by Adam Singer

  I recently purchased Drew Wilson's Pictos icon library. It is a library of flat, monochromatic icons for use on the web and elsewhere. The only issue is: they're vectors. I know my way around Illustrator a little bit, but ultimately I want to import these icons into Photoshop and resize to various dimensions. The problem I'm having: when I import an icon and resize it to, say, 20x20 pixels, I notice that there is a fair bit of aliasing around the edges of the icon. I'm sure there is some magic number where the edges of these icons will remain crisp, but I can't find any option or setting that will allow me to size these icons properly. Is there a way in Photoshop to snap these icons to the closest size that removes or minimizes the aliasing?

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