# HG changeset patch
# User Rik <octave@nomad.inbox5.com>
# Date 1301581991 25200
# Node ID 4040a95a586d0361ae16b9e914b61145f436bc37
# Parent  7c915d013b9c75dc183d79b3534bccd8ede63a80
Revamp quiver autoscaling algorithm (bug #32836).

diff -r 7c915d013b9c -r 4040a95a586d scripts/ChangeLog
--- a/scripts/ChangeLog	Thu Mar 31 07:13:33 2011 -0700
+++ b/scripts/ChangeLog	Thu Mar 31 07:33:11 2011 -0700
@@ -1,3 +1,7 @@
+2011-03-31  Rik  <octave@nomad.inbox5.com>
+
+	* plot/private/__quiver__.m: Revamp autoscaling algorithm (bug #32836).
+
 2011-03-29  John W. Eaton  <jwe@octave.org>
 
 	* special-matrix/wilkinson.m: Update test for 'wilkinson(1)' to reflect
diff -r 7c915d013b9c -r 4040a95a586d scripts/plot/private/__quiver__.m
--- a/scripts/plot/private/__quiver__.m	Thu Mar 31 07:13:33 2011 -0700
+++ b/scripts/plot/private/__quiver__.m	Thu Mar 31 07:33:11 2011 -0700
@@ -107,18 +107,27 @@
 
   if (autoscale && numel (u) > 1)
     ## Scale the arrows to fit in the grid
-    dx = (max(x(:)) - min(x(:))) ./ size (x, 2);
-    dy = (max(y(:)) - min(y(:))) ./ size (y, 1);
+    if (isvector (x))
+      ny = nx = length (x);
+    else
+      [nx, ny] = size (x);
+    endif
+    dx = (max(x(:)) - min(x(:))) ./ nx;
+    dy = (max(y(:)) - min(y(:))) ./ ny;
     if (is3d)
-      ## What should this be divided by? The below seems right
       dz = (max(z(:)) - min(z(:))) ./ max (size (z));
-      len = max (sqrt (u(:).^2 + dy(:).^2) + dz(:).^2);
+      len = max (sqrt (u(:).^2 + v(:).^2 + w(:).^2));
     else
-      len = max (sqrt (u(:).^2 + dy(:).^2));
       dz = 0;
+      len = max (sqrt (u(:).^2 + v(:).^2));
     endif
     if (len > 0)
-      s = 2 * autoscale / sqrt (2) * sqrt (dx.^2 + dy.^2 + dz.^2) / len;
+      sd = sqrt (dx.^2 + dy.^2 + dz.^2) / len;
+      if (sd != 0)
+        s = sqrt(2) * autoscale * sd;
+      else # special case of identical points with multiple vectors 
+        s = autoscale; 
+      endif
       uu = s * u;
       vv = s * v;
       if (is3d)
@@ -335,18 +344,25 @@
 
   if (strcmpi (get (h, "autoscale"), "on") && s != 0)
     ## Scale the arrows to fit in the grid
-    dx = (max(x(:)) - min(x(:))) ./ size (x, 2);
-    dy = (max(y(:)) - min(y(:))) ./ size (y, 1);
+    if (isvector (x))
+      ny = nx = length (x);
+    else
+      [nx, ny] = size (x);
+    endif
+    dx = (max(x(:)) - min(x(:))) ./ nx;
+    dy = (max(y(:)) - min(y(:))) ./ ny;
     if (is3d)
-      ## What should this be divided by? The below seems right
       dz = (max(z(:)) - min(z(:))) ./ max (size (z));
-      len = max (sqrt (u(:).^2 + dy(:).^2) + dz(:).^2);
+      len = max (sqrt (u(:).^2 + v(:).^2 + w(:).^2));
     else
-      len = max (sqrt (u(:).^2 + dy(:).^2));
       dz = 0;
+      len = max (sqrt (u(:).^2 + v(:).^2));
     endif
     if (len > 0)
-      s = 2 * s / sqrt (2) * sqrt (dx.^2 + dy.^2 + dz.^2) / len;
+      sd = sqrt (dx.^2 + dy.^2 + dz.^2) / len;
+      if (sd != 0)
+        s *= sqrt(2) * sd;
+      endif
       u = s * u;
       v = s * v;
       if (is3d)