[Octave-bug-tracker] [bug #55389] Performance of movXXX functions

[Rik]

URL:
  <https://savannah.gnu.org/bugs/?55389>

                 Summary: Performance of movXXX functions
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Fri 04 Jan 2019 10:30:41 AM PST
                Category: Performance
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: Confirmed
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

The performance of certain of the movXXX functions for the most common case of
"shrink" Endpoints can be improved by ~4X by using an equivalent formulation
which pads the original data.

Below is an example with a 1000x1000 array x.


octave:4> tic; y = movmin (x, 51, 'Endpoints', "shrink"); toc
Elapsed time is 0.989651 seconds.
octave:5> tic; y = movmin (x, 51, 'Endpoints', Inf); toc
Elapsed time is 0.262563 seconds.


Code needs to be written that checks the input arguments to the movXXX
function and if the "Endpoints" value is "shrink" or non-existent then it
substitutes a specific fill value.  The fill values are movmax (-Inf), movmin
(Inf), movprod (1), and movsum (0).





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