Algorithm for Matlab conv function

I would like to know which algorithm (or at least which big-O) is used in the built-in conv function. Thanks, Federico Labriola

Answer 1

[John D'Errico]

Why not test it yourself? These things are always SOOOO much more easily checked by yourself, rather than waiting for a response.

n = 10000;
a = rand(n,1);b = rand(n,1);
t(1) = timeit(@() conv(a,b));
a = rand(2*n,1);b = rand(2*n,1);
t(2) = timeit(@() conv(a,b));
a = rand(4*n,1);b = rand(4*n,1);
t(3) = timeit(@() conv(a,b));
a = rand(8*n,1);b = rand(8*n,1);
t(4) = timeit(@() conv(a,b));

t
t =
     0.011539     0.056427       0.2248      0.88019

exp(diff(log(t)))
ans =
       4.8901        3.984       3.9154

Looks like factors of 4 for each step to me.