矩阵中元素的加权和 - Matlab？
我有两个 50 x 6 矩阵，例如 A 和 B。我想为矩阵中列的每个元素分配权重 - 对列中较早出现的元素赋予更大的权重，对同一列中较晚出现的元素赋予较小的权重......对于所有 6 列也是如此。像这样：
cumsum(weight(row)*(A(row,col)-B(row,col)); % cumsum is for cumulative sum of matrix
我们如何在不使用循环的情况下有效地完成它？
I have two 50 x 6 matrices, say A and B. I want to assign weights to each element of columns in matrix - more weight to elements occurring earlier in a column and less weight to elements occurring later in the same column...likewise for all 6 columns. Something like this:
cumsum(weight(row)*(A(row,col)-B(row,col)); % cumsum is for cumulative sum of matrix
How can we do it efficiently without using loops?
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如果您将权重向量
w作为50x1向量，那么您可以将代码重写为BTW，我不知道为什么您有
cumsum 在循环中对标量进行操作...它没有效果。我假设您的意思是您希望对整个矩阵执行此操作。默认情况下，在矩阵上调用 cumsum 将会沿每一列进行运算。如果您需要沿行进行操作，则应使用可选的维度参数来调用它，如 cumsum(x,2)，其中x是您拥有的任何矩阵。If you have your weight vector
was a50x1vector, then you can rewrite your code asBTW, I don't know why you have the
cumsumoperating on a scalar in a loop... it has no effect. I'm assuming that you meant that's what you wanted to do with the entire matrix. Callingcumsumon a matrix will operate along each column by default. If you need to operate along the rows, you should call it with the optional dimension argument ascumsum(x,2), wherexis whatever matrix you have.