笛卡爾乘積的Matlab向量化

Question

假設我有兩個數組X和Y，我需要一個矩陣M（i，j）= some_func（X（i），Y（j））。我怎樣才能不使用循環？

Answer 1

最好的答案是使用bsxfun，如果它是一個選項。按照幫助bsxfun，它完全可以在任何普通的二元函數，只要：

FUNC can also be a handle to any binary element-wise function not listed 
    above. A binary element-wise function in the form of C = FUNC(A,B) 
    accepts arrays A and B of arbitrary but equal size and returns output 
    of the same size. Each element in the output array C is the result 
    of an operation on the corresponding elements of A and B only. FUNC must 
    also support scalar expansion, such that if A or B is a scalar, C is the 
    result of applying the scalar to every element in the other input array. 

如果你的函數只接受標量輸入，然後循環是簡單的替代品。

Answer 2

很難回答你的模糊問題，它最終取決於你的功能。您可以做的是使用meshgrid然後執行操作，通常使用點運算符

x = 1:5; 
y = 1:3; 

[X,Y] = meshgrid (x,y) 

M = X.^Y;