将2D矩阵与向量相乘以跨越三维-MATLAB [英] Multiply 2D Matrix with vector to span third dimension - MATLAB

问题描述

当我尝试将m x n矩阵与p-dimensional向量相乘时，我遇到了一些困难.

As I am trying to multiply a m x n Matrix with a p-dimensional vector, I am stumbling across some difficulties.

尝试避免for循环，这是我要实现的目标

Trying to avoid for loops, here is what I am looking to achieve

enter code here
M = [1 2 3;                   p = [1;2;3]
     4 5 6;
     7 8 9]

我想获得一个3x3x3矩阵，其中三维中的切片只是M的条目乘以p中的相应条目.

I want to obtain a 3x3x3 matrix, where the slices in third dimension are simply the entries of M multiplied by the respective entry in p.

非常感谢您的帮助

推荐答案

您可以使用 bsxfun 和 permute 表示<像这样的href ="http://in.mathworks.com/help/matlab/matlab_prog/vectorization.html" rel ="noreferrer"> vectorized (无循环)方法-

You can use bsxfun with permute for a vectorized (no-loop) approach like so -

out = bsxfun(@times,M,permute(p(:),[3 2 1]))

您最终会得到-

out(:,:,1) =
     1     2     3
     4     5     6
     7     8     9
out(:,:,2) =
     2     4     6
     8    10    12
    14    16    18
out(:,:,3) =
     3     6     9
    12    15    18
    21    24    27

---

使用matrix-multiplication-

out = permute(reshape(reshape(M.',[],1)*p(:).',[size(M) numel(p)]),[2 1 3])

这篇关于将2D矩阵与向量相乘以跨越三维-MATLAB的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！