bugGNU Octave - Bugs: bug #60426, patch: huge speed-up of pchip for...

 
 

bug #60426: patch: huge speed-up of pchip for mixed precision arguments

Submitter:  A.R. Burgers <arb>
Submitted:  Tue 20 Apr 2021 08:32:48 PM UTC
   
 
Category:  Performance Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Performance
Status:  None Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
* Mandatory Fields

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Tue 20 Apr 2021 08:32:48 PM UTC, original submission:  

as explained in bug #60361 pchip is very slow for mixed precision x and y arguments. The attached changeset fixes this, by replacing the division by a diagonal matrix with broadcast and scalar division.


   ## This is taken from SLATEC.
-  h = diag (h);
+  hr = 1.0 ./ h;

-  delta = diff (y, 1, 2) / h;
-  del1 = (d1 - delta) / h;
-  del2 = (d2 - delta) / h;
+  delta = diff (y, 1, 2) .* hr;
+  del1 = (d1 - delta) .* hr;
+  del2 = (d2 - delta) .* hr;
   c3 = del1 + del2;
   c2 = -c3 - del1;
-  c3 /= h;
+  c3 .*= hr;
   coeffs = cat (3, c3, c2, d1, f1);


A.R. Burgers <arb>

 

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Attached Files
file #51300:  p29634_pchip.txt added by arb (996B - text/plain)

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-04-20 arb Attached File- Added p29634_pchip.txt, #51300

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