Fix colormap functions when N is not of class double (bug #44070) * autumn.m, bone.m, cool.m, copper.m, cubehelix.m, gray.m, hsv.m, ocean.m, rainbow.m, spring.m, summer.m, winter.m: cast N to double since in this colormap functions, N is used directly used in the operations and ends up casting colormap to something else. Note that a colormap MUST be of class double. Also, if N is an integer class, all values in colormap end up 0 or 1. Also simplify code for input checking by declaring default on function signature line. * flag.m, gmap40.m, hot.m, jet.m, lines.m, pink.m, prism.m, white.m: simplify input check like the other colormap functions. * test/colormaps.tst: add new test file to test all colormaps at once. * test/Makefile.am: add new test file to build system. used to create the colormap and if less

--- a/scripts/image/copper.m
+++ b/scripts/image/copper.m
@@ -31,17 +31,14 @@
 ## PKG_ADD: colormap ("register", "copper");
 ## PKG_DEL: colormap ("unregister", "copper");
 
-function map = copper (n)
+function map = copper (n = rows (colormap ()))
 
-  if (nargin == 0)
-    n = rows (colormap);
-  elseif (nargin == 1)
-    if (! isscalar (n))
-      error ("copper: N must be a scalar");
-    endif
-  else
+  if (nargin > 1)
     print_usage ();
+  elseif (! isscalar (n))
+    error ("copper: N must be a scalar");
   endif
+  n = double (n);
 
   if (n == 1)
     map = [0, 0, 0];
@@ -58,7 +55,6 @@
 
 endfunction
 
-
 %!demo
 %! ## Show the 'copper' colormap as an image
 %! image (1:64, linspace (0, 1, 64), repmat ((1:64)', 1, 64));