Hey there,
I wrote a short code to mimic the build-in ListConvolve function. I compiled the code into "c" with the
Compile function. I would like to know why
ListConvolve is still so much faster on large list. (You should have a proper C compiler installed to run this code, otherwise wolfram virtural machine is used)
Clear[cf]
cf = Compile[{{x, _Real, 1}, {n, _Integer}},
Module[{l = {}, temp = 0.},
Do[
(Do[temp = temp + x[[i]];,
{i, k, k + n - 1}]);
l = Append[l, 1/n*temp];
temp = 0.;,
{k, 1, Length[x] - n + 1}
];
Return[l]
], CompilationTarget -> "C"
]
I compare the time required to run these two codes:
data = RandomReal[{1, 10}, 100000];
cf[data, 3];
ListConvolve[1/3.*{1, 1, 1}, data];
No need to use timing function, the difference is definitely noticeable as the length of data is greater than 10^4.
I am curious about what is behind the ListConvolve function.
