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Locating global max in 3D plot

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John Paul
John Paul on 22 Jan 2021
Commented: Star Strider on 23 Jan 2021
I'm working on some MATLAB code but I have encountered a problem that has hindered my progress.
Kindly would you assist me on how I may locate a global maxima value in a case where I have more than one maximas in a 3D plot.
I'm using this
Idx = find((Pmusic(:) == max(max(Pmusic(:)))));
[PmusicmaxRow,PmusicmaxCol] = ind2sub(size(Pmusic), Idx);
but it brings all the maximas but I am only interested with the indices of the global maxima.

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Star Strider
Star Strider on 22 Jan 2021
Try this:
[maxval,Idx] = max(Pmusic(:));
[PmusicmaxRow,PmusicmaxCol] = ind2sub(size(Pmusic), Idx);
I obviously cannot test this with your matrix, however it worked correctrly when I tested it with my test matrix.

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Star Strider
Star Strider on 23 Jan 2021
The max function will only return the first maximum (and the index), in the event that there are more than one. However here, there apopears to be only one maximum.
When I run:
[maxval,Idx] = max(Pmusic(:));
[PmusicmaxRow,PmusicmaxCol] = ind2sub(size(Pmusic), Idx);
maxidxv = find(Pmusic == maxval);
the only maximum value is 18.7194, and the index is 8752. The find call (that I added here temporarily) also only detects the same one maximum, with the same index. The ‘aaa’ and ‘ccc’ vectors are simply repeats of the row and column indices, not new or different indices. So ‘aaa’ is a (1x10) vector of 63, and ‘ccc’ is a (1x10) vector of 48.
There are no local maxima, only one global maximum.
I did not examine all your code, only the part you have questions about, those lines 126 and 127 of the file you attached.
John Paul
John Paul on 23 Jan 2021
Respected Sir, You are absolutely correct. This section of the code is supposed to genereate indices for the global maximas for 10 iterations and that is the reason ‘aaa’ and ‘ccc’ are (1x10) vectors. Thank you so much for your invalauble advice. You have made me move a step further with my work.
Star Strider
Star Strider on 23 Jan 2021
As always, my pleasure!
I am always happy to help!

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