Help vectorizing calculation that accesses multiple entries in the input array and the previous element of the output array

Question

0 个投票

I'm wondering if this can be vectorized. I'm accessing two entries in the input array along with the previous entry in the output array.

v and T are a vectors of floats.

[Edit: I left out some complexity and I'm not sure if the answer given can still be applied. I've updated the code below with the full expression.]

out = zeros(length(v), 1);
out(1) = 1;
for i = 2:length(v)
    out(i) = out(i - 1) * (v(i) / v(i - 1)) * (T(i) / T(i - 1));
end

2 个评论
显示无隐藏无

Jan 2021-3-22

Note: Avoid the square brackets around the counter in FOR loops. They can impede the JIT acceleration. Prefer:

for i = 2:length(v)

Thanks for the tip!

Answer 1

Matt J 2021-3-19

1 个投票

out=v./v(1)

Matt J 2021-3-22

It still looks like it will just be,

Tv=T.*v;
out=TV./Tv(1)

You are correct, I see what's happening now. Thanks for your help!