Is there a multiplicative accumarray function?

Question

Christopher 2014-3-14

编辑： the cyclist 2014-3-14

I am using accumarray to additively accumulate numbers with a code like the following:

wts = accumarray([P(:,2),P(:,1)],P(:,3),size(net));

Is there a function, or a simple vectorized method, to do the exact same thing with one difference: instead of adding the numbers, multiply them?

If accumarray finds numbers N1, N2, N3... it will add them as N1+N2+N3...

However, I want a function to multiply them as N1*N2*N3...

Thanks

Answer 1

the cyclist 2014-3-14

编辑：the cyclist 2014-3-14

accumarray() takes an optional fourth argument, which is the function to apply. You should be able to add @prod to do what you want.

Here is the example from the documentation:

val = 101:105;
subs = [1 1; 2 1; 2 3; 2 1; 2 3];
A = accumarray(subs, val, [2 4], @prod, 0, true)

Read

doc accumarray

for details.