[Octave-bug-tracker] [bug #49076] Should perform matrix chain multiplication optimization

[Bernardo Sulzbach]

Follow-up Comment #2, bug #49076 (project octave):

I understand your concerns. However, this is not meant to be a new default
behavior. I would like this to be a function provided by octave. Using the *
with matrices should still call mtimes and not this new function.

After rereading my last paragraph I see that it only hints at a different
function calling mtimes. However, I don't mean that multiple usages of *
should lead into a call to this function rather than mtimes. I am not
proposing any changes to the current behavior of matrix multiplication in
Octave.

The main point of the enhancement is to allow more efficient code for large
enough matrices where overflow should not happen without requiring men hours
to optimize the order manually when the optimization is not trivial.

----

As a last note, you are referring to -fassociative-math (and some other
options) which allow the compiler to assume that FP math is associative. The
optimizations I am talking about will, evidently, reorder multiplications.
This is just another reason not to make this behavior the new default, which I
don't want it to become.

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