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changeset 15707:d803cd07f31a

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Tweak C++ implementation of jet colormap to produce exactly the same result as jet.m * graphics.cc (jet_colormap): Create the index entry x in the same manner as linspace so that jet_colormap() produces the same results as jet.m.
author Rik <rik@octave.org>
date Fri, 30 Nov 2012 13:21:15 -0800
parents 242e9efd4315
children 916ef285522a
files libinterp/interpfcn/graphics.cc
diffstat 1 files changed, 5 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/libinterp/interpfcn/graphics.cc	Sun Sep 02 16:21:48 2012 -0300
+++ b/libinterp/interpfcn/graphics.cc	Fri Nov 30 13:21:15 2012 -0800
@@ -137,6 +137,10 @@
 {
   Matrix cmap (64, 3, 0.0);
 
+  // Produce X in the same manner as linspace so that 
+  // jet_colormap and jet.m produce *exactly* the same result.
+  double delta = 1.0 / 63.0;
+
   for (octave_idx_type i = 0; i < 64; i++)
     {
       // This is the jet colormap.  It would be nice to be able
@@ -146,7 +150,7 @@
       // called, so calling an interpreted function is not
       // possible.
 
-      double x = i / 63.0;
+      double x = i*delta;
 
       if (x >= 3.0/8.0 && x < 5.0/8.0)
         cmap(i,0) = 4.0 * x - 3.0/2.0;