matrix

Is there a standard solution for Gauss elimination in Python?

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I finally found, that it can be done using LU decomposition. Here the U matrix represents the reduced form of the linear system. from numpy import array from scipy.linalg import lu a = array([[2.,4.,4.,4.],[1.,2.,3.,3.],[1.,2.,2.,2.],[1.,4.,3.,4.]]) pl, u = lu(a, permute_l=True) Then u reads array([[ 2., 4., 4., 4.], [ 0., 2., 1., 2.], [ 0., 0., … Read more

Differences of using “const cv::Mat &”, “cv::Mat &”, “cv::Mat” or “const cv::Mat” as function parameters?

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It’s all because OpenCV uses Automatic Memory Management. OpenCV handles all the memory automatically. First of all, std::vector, Mat, and other data structures used by the functions and methods have destructors that deallocate the underlying memory buffers when needed. This means that the destructors do not always deallocate the buffers as in case of Mat. … Read more

Finding neighbor cells in a grid with the same value. Ideas how to improve this function?

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Here’s an approach that involves less copying and pasting — hopefully it gives you some idea of how to break things down into the smallest number of the most reusable pieces possible. 🙂 The general idea here is to come up with a way of expressing the concept of scanning a line across the board … Read more

How performing multiple matrix multiplications in CUDA?

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I think it’s likely that the fastest performance will be achieved by using the CUBLAS batch gemm function which was specifically designed for this purpose (performing a large number of “relatively small” matrix-matrix multiply operations). Even though you want to multiply your array of matrices (M[]) by a single matrix (N), the batch gemm function … Read more

Matlab: repeat every column sequentially n times [duplicate]

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Suppose you have this simplified input and you want to expand columns sequentially n times: A = [1 4 2 5 3 6]; szA = size(A); n = 3; There are few ways to do that: Replicate, then reshape: reshape(repmat(A,n,1),szA(1),n*szA(2)) Kronecker product: kron(A,ones(1,n)) Using FEX: expand(): expand(A,[1 n]) Since R2015a, repelem(): repelem(A,1,n) All yield the … Read more

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