# I have a mistake in loops

2 views (last 30 days)
sznailc on 5 Nov 2021
Edited: Stephen23 on 5 Nov 2021
Hello, I have somewhere a mistake that if N = 1000 the output misses some lines (don't know which), so I suppose there's a mistake somewhere in for loops. It works correctly with N = 50, 100, 500.
function [R, I] = problem2B(N)
I = 0;
for a = 3:N
for b = a:N
for c = b:N
if (a^2 + b^2) == c^2 && a+b+c < N
R(I+1, :) = [a+b+c, a, b, c];
I = I + 1;
elseif N < 12
R = zeros(4, 1);
end
end
end
end
if N <= 50
R = reshape(nonzeros(R), I, 4);
else
R = sortrows(R, 1);
end
end
##### 3 CommentsShow 1 older commentHide 1 older comment
sznailc on 5 Nov 2021
Edited: sznailc on 5 Nov 2021
I have a test file that says, that not all possible pythagorean triples are displayed with N = 1000. Therefore I think there has to be a mistake with indexes that it skips some possible triples.
Stephen23 on 5 Nov 2021
Edited: Stephen23 on 5 Nov 2021
Note that if you change to
R = zeros(0,4);
then you can get rid of NONZEROS and RESHAPE.

Steven Lord on 5 Nov 2021
Does your problem ask you to find all Pythagorean triples whose elements sum to less than 1000 or all whose elements sum to less than or equal to 1000?
sznailc on 5 Nov 2021
wow, thank you, edited to a+b+c <= N. I couldn't tell what triple is missing and didn't know that it might be 1000

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