How to construct a customized outer function for 2 vectors?

Hi,

I have 2 vectors, namely A (dim n) and B (dim m). I want to have some customized outer functions to give me an output of m*n matrix. For example,

A=[7,8,9];
B=[2,1,0,-1]';

C=zeros(4,3);
for i=1:4
    C(i,:)=A.^B(i);
end
C

But I don't want a for-loop. Instead, I want to vectorize the calculation. Thus I tried this:-

D=exp(B*log(A))

D is better than C, since C needs a for-loop while D doesn't. But D is still not good enough, since it needs a transformation of log() and exp(). How can I get rid of the transformations, and produce the direct outer product of A.^B (or any other customized outer output f(A,B))?

Many thanks!

Answer 1

[James Tursa]

Start with a vectorized function handle, e.g.,

f = @(x,y)x.^y

Then use bsxfun, e.g.,

result = bsxfun(f,A,B);

Note that for later versions of MATLAB, this implicit expansion capability is built-in to several MATLAB operators and bsxfun would not be needed.