[Octave-bug-tracker] [bug #52919] comparison of complex values

[Rik]

Follow-up Comment #12, bug #52919 (project octave):

Irrespective of the sorting order, it does seem like sorting of complex
numbers is rather slow.

I used the following test code which is also attached


N = 1e3;

x = [1e6:-1:1]';
y = x + 1i;
z = zeros (size (x));

bm1 = bm2 = bm3 = zeros (N,1);
for i = 1:N
  tic;
  z = sort (x);
  bm1(i) = toc;
  tic;
  z = sort (y);
  bm2(i) = toc;
  tic;
  z = sort (abs (y));
  bm3(i) = toc;
endfor

mean (bm1)
mean (bm2)
mean (bm3)


The results were


ans =  0.0028022
ans =  0.025930
ans =  0.011031


So sorting of complex numbers is about 10X slower than reals.  And more
importantly, it is abot 2.5X slower than the equivalent sort (abs (y))
command.  The y values chosen all differ in abs() so it is not a question of
extra processing of the phase angle.  It seems there are just a lot of hoops
to go through before the correct code is engaged. 


(file #42980)
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Additional Item Attachment:

File name: bm_sort.m                      Size:0 KB


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