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For loop within for loop

Asked by DARLINGTON ETAJE on 8 Aug 2019
Latest activity Answered by Jos (10584)
on 9 Aug 2019
Please help me out. This code isn't working...
qq=8:10008;
for m = 1:9
for n = 1:10001
A(m, n) = (m+n)+qq;
end
end
I just want answer for A

  3 Comments

Adam
on 8 Aug 2019
No idea what answer you want since you didn't tell us and you already said the code isn't working so there's not much point us looking at that to understand what you want.
However, you are adding a vector, qq, to a scalar (m+n) and trying to assign the result of this to a scalar A(m,n) which clearly will not work. At a guess you want to add qq(n) instead.
You just solved the problem...qq(n) works....thank you.
Alex Mcaulley on 9 Aug 2019
You can do it without loop. For example:
qq = 8:10008;
n = 1:10001;
m = 1:9;
[X,Y] = meshgrid(qq + n,m)
A = X + Y;
If you use the loops, at least preallocate your array A to minimize the execution time:
qq = 8:10008;
A = zeros(9,10001);
for m = 1:9
for n = 1:10001
A(m, n) = (m+n)+qq(n);
end
end

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1 Answer

Answer by Jos (10584)
on 9 Aug 2019

In recent ML versions there is no need for meshgrid or so. The plus syntax will expand the vectors :-)
% a smaller example
n = 1:11
m = 1:4
q = 8:18
A = m' + n + q

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