I tried to generate a sequence with a specific interval, but the output skips some intervals.

mat = [];

interval = -0.10;

max = 1.00;

i = 0;

for a=1.00:interval:0.00

for b=1.00:interval:0.00

for c=1.00:interval:0.00

if a+b+c == max

mat(i+1,:) = [a,b,c];

i=i+1;

end

end

end

end

mat

[Fortia Alfeche]

This is suppose to generate 66 combinations, but i'm getting less

[Stephen23]

Note that you can easily get rid of the loops:

mxv = 1;
[X,Y,Z] = ndgrid(0:0.1:1);
M = [X(:),Y(:),Z(:)];
M(abs(sum(M,2)-mxv)>1e-9,:) = []

M = 66×3

1.0000 0 0 0.9000 0.1000 0 0.8000 0.2000 0 0.7000 0.3000 0 0.6000 0.4000 0 0.5000 0.5000 0 0.4000 0.6000 0 0.3000 0.7000 0 0.2000 0.8000 0 0.1000 0.9000 0

And there are your 66 triples :)

Answer 1

[DGM]

I missed the comparison.

You're dealing with floating-point numbers. You can expect exact equality tests to fail due to rounding errors. This comment contains a number of links to related threads on the topic. Other people have explained it better than I can.

https://www.mathworks.com/matlabcentral/answers/1771170-infinite-loop-when-decimals-are-added#comment_2292205

You can test for equality within some tolerance

mat = [];
interval = -0.10;
maxval = 1.00;
i = 0;
for a=1.00:interval:0.00
    for b=1.00:interval:0.00
        for c=1.00:interval:0.00
            thissum = a+b+c;
            if abs(thissum-maxval) < 1E-14
                mat(i+1,:) = [a,b,c];
                i=i+1;
            end
        end
    end
end
mat

mat = 66×3

1.0000 0 0 0.9000 0.1000 0 0.9000 0 0.1000 0.8000 0.2000 0 0.8000 0.1000 0.1000 0.8000 0 0.2000 0.7000 0.3000 0 0.7000 0.2000 0.1000 0.7000 0.1000 0.2000 0.7000 0 0.3000

[Fortia Alfeche]

Thank you very much!