# Vector indexing inefficiency question.

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Daniel on 3 Jun 2014
Commented: Daniel on 3 Jun 2014
Hi all,
I am having performance issues with matlab and I was wondering if anybody had any ideas to speed up my algorithm
I have four vectors, a,b,c,d each of varying lengths. Each value inside the vectors represents a particular angle.
a = [1 2 3 5]
b = [2 52 53 51 55 66]
c = [1]
d = [3 6 9]
A set of four values from A, B, C, D represents a particular geometry I need to evaluate. For example, [1 52 1 9] is a geometry [2 2 1 6] is a geometry etc.... I need to do this for every possible combination of geometry available.
currently I have a bunch of nested for loops, and while I know this is inefficient, it helps me for debugging and I wasn't sure how to vectorize when you need to do each geometry, especially when the vectors are of varying lengths.
Anybody have any good ideas?
Thanks,
Dan
##### 2 CommentsShowHide 1 older comment
Daniel on 3 Jun 2014
a = [1 2 3 5]
b = [2 52 53 51 55 66]
c = [1]
d = [3 6 9]
for i = 1:length(a)
for j = 1: length(b)
for k = 1: length(c)
for r = 1: length(d)
data = function( a(i), b(j), c(k) d(r) )
end
end
end
end
What I'm trying to do is get rid of these for loops

Mahdi on 3 Jun 2014
Have you looked at perms built-in function? I'm sure you can manipulate to fulfill your need.
##### 2 CommentsShowHide 1 older comment
Mahdi on 3 Jun 2014
No problem.

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