[bug #68121] convert isequal to built-in function for performance

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Follow-up Comment #2, bug #68121 (group octave):

Hi Dr. Jankowski:

Thanks for the quick response.

I'm not doing anything fancy, just checking over a million 9x9 matricies with
elements 0-9.  It SHOULD be much faster to do isequal(M1,M2) versus
all(all(M1==M2)) [fn1] because a built-in wouldn't actually do 81 comparisons
before quick exiting if any element were not the same. [fn2]

Again, I'm unfamiliar with Octave source code, but a built-in isequal(n) [fn3]
should be simpler than the .m file version.  Whatever internal data structure
Octave has should be easier to work with than all the possible MATLAB/Octave
data types (classes).  I'm guessing that, internally, Octave workspace
variables are pointers to some uniform data structure/object, right?  Let's
call it an OctaveVariable object. [fn4]  If the pointers are the same,
isequaln is a quick exit true, right? [fn5]  But, if they aren't, it should be
easy enough to compare all OctaveVariable fields/members and recurse if
necessary.

Sorry if my assumptions are naive/wrong.
Andy

[fn1] In my case about 80-81 times faster.

[fn2] While for-loops are slow in MATLAB/Octave, they are fast in source code
(C/C++).

[fn3] If isequal gets implemented as a built-in, you'll also be able to
implement isequaln for insignificant additional time.  ;-)

[fn4] Just FMI, what is the actual name of the object?

[fn5] Perhaps isequal would have to drill in?  Or does your OctaveVarible has
a boolean field called something like AnyNaNAnywhere.







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