在MATLAB中进行向量化的简介-有什么好的教程吗? [英] Introduction to vectorizing in MATLAB - any good tutorials?

问题描述

我正在寻找有关MATLAB中向量化(循环)的任何优秀教程.

I'm looking for any good tutorials on vectorizing (loops) in MATLAB.

我有一个非常简单的算法，但是它使用了两个for循环.我知道将其向量化应该很简单，我想学习如何做到这一点，而不是要求您提供解决方案.

I have quite simple algorithm, but it uses two for loops. I know that it should be simple to vectorize it and I would like to learn how to do it instead of asking you for the solution.

但是，为了让您知道我遇到了什么问题，因此您可以建议展示如何解决类似问题的最佳教程，这是我的问题的概述:

But to let you know what problem I have, so you would be able to suggest best tutorials that are showing how to solve similar problems, here's the outline of my problem:

B = zeros(size(A));    % //A is a given matrix.
for i=1:size(A,1)
   for j=1:size(A,2)
      H = ... %// take some surrounding elements of the element at position (i,j) (i.e. using mask 3x3 elements)
      B(i,j) = computeSth(H); %// compute something on selected elements and place it in B
   end
end

所以，我不要求解决方案.我要一个好的教程，MATLAB中向量化循环的示例.我想学习如何做以及自己做.

So, I'm NOT asking for the solution. I'm asking for a good tutorials, examples of vectorizing loops in MATLAB. I would like to learn how to do it and do it on my own.

推荐答案

以下是我经常链接到的两个MathWorks教程作为该主题的参考:

Here are a couple of MathWorks tutorials I often link to as references on the subject:

• 代码矢量化指南
• 提高性能的技术:矢量化循环

• Code Vectorization Guide
• Techniques for Improving Performance: Vectorizing Loops

这是Loren的博客文章之一，针对特定的示例问题提供了很好的代码矢量化演练:

And here's one of Loren's blog posts that has a nice walkthrough of code vectorization for a particular sample problem:

• 加速MATLAB应用程序

您作为样本给出的特定类型的问题，涉及处理给定矩阵的子矩阵，可以根据您所执行的哪种操作，以不同的方式将其向量化.您可能可以使用 CONV2 或 FILTER2 而不是嵌套的for循环. 图像处理工具箱中还有许多功能可以处理矩阵的邻域和块处理，例如 NLFILTER 和

The particular type of problem you gave as a sample, which involves processing submatrices of a given matrix, could be vectorized in different ways depending greatly on what sort of operation you are doing. You may be able to use CONV2 or FILTER2 instead of your nested for loops. There are also a number of functions in the Image Processing Toolbox that handle neighborhood and block processing of matrices, such as NLFILTER and BLOCKPROC. The documentation for these functions should help you figure out how to use them as a way to vectorize your code.

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