[genius] Thu Oct 24 23:51:15 2013 Jiri (George) Lebl <jirka 5z com>

[George Lebl <jirka src gnome org>]

commit 53314446be0d0d1e1989e73ac129deca10d52ead
Author: Jiri (George) Lebl <jirka 5z com>
Date:   Thu Oct 24 23:51:19 2013 -0500

    Thu Oct 24 23:51:15 2013  Jiri (George) Lebl <jirka 5z com>
    
        * src/graphing.c: better detection of jumps due to vertical
          asymptotes to avoid drawing the vertical lines

 ChangeLog      |    5 +++++
 src/graphing.c |   23 +++++++++++++----------
 2 files changed, 18 insertions(+), 10 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 7ac82f5..a64efec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct 24 23:51:15 2013  Jiri (George) Lebl <jirka 5z com>
+
+       * src/graphing.c: better detection of jumps due to vertical
+         asymptotes to avoid drawing the vertical lines
+
 Sun Oct 20 23:44:25 2013  Jiri (George) Lebl <jirka 5z com>
 
        * lib/equation_solving/newton.gel: Add HalleysMethod
diff --git a/src/graphing.c b/src/graphing.c
index 22b6ff3..085f50f 100644
--- a/src/graphing.c
+++ b/src/graphing.c
@@ -4399,11 +4399,11 @@ recompute_function (int funci, double **x, double **y, int *len, gboolean fittin
                        continue;
                }
 
-               xdiffscaled = fabs(nextpt->x-pt->x)/sizex;
-               ydiffscaled = fabs(nextpt->y-pt->y)/sizey;
+               xdiffscaled = (nextpt->x-pt->x)/sizex;
+               ydiffscaled = (nextpt->y-pt->y)/sizey;
 
                /* derivative at least 100 after scaling, length bigger than 1% */
-               if (100.0*xdiffscaled < ydiffscaled &&
+               if (100.0*fabs(xdiffscaled) < fabs(ydiffscaled) &&
                    xdiffscaled*xdiffscaled+ydiffscaled*ydiffscaled > 0.01*0.01 &&
                    li->next->next != NULL && li->prev != NULL) {
                        Point *prevpt = li->prev->data;
@@ -4413,16 +4413,19 @@ recompute_function (int funci, double **x, double **y, int *len, gboolean fittin
                        double xprevdiffscaled;
                        double yprevdiffscaled;
 
-                       xnextdiffscaled = fabs(nextnextpt->x-nextpt->x)/sizex;
-                       ynextdiffscaled = fabs(nextnextpt->y-nextpt->y)/sizey;
+                       xnextdiffscaled = (nextnextpt->x-nextpt->x)/sizex;
+                       ynextdiffscaled = (nextnextpt->y-nextpt->y)/sizey;
 
-                       xprevdiffscaled = fabs(pt->x-prevpt->x)/sizex;
-                       yprevdiffscaled = fabs(pt->y-prevpt->y)/sizey;
+                       xprevdiffscaled = (pt->x-prevpt->x)/sizex;
+                       yprevdiffscaled = (pt->y-prevpt->y)/sizey;
 
 
-                       /* too steep! and steeper than surrounding which is derivative at most 10 */
-                       if (10.0*xprevdiffscaled >= yprevdiffscaled && 
-                           10.0*xnextdiffscaled >= ynextdiffscaled) {
+                       /* too steep! and steeper than surrounding which is derivative at most 10,
+                        * or if the prev and next derivatives are of different sign */
+                       if ( (10.0*fabs(xprevdiffscaled) >= fabs(yprevdiffscaled) && 
+                             10.0*fabs(xnextdiffscaled) >= fabs(ynextdiffscaled)) ||
+                            ( ydiffscaled > 0.0 && ynextdiffscaled < 0.0 && yprevdiffscaled < 0.0) ||
+                            ( ydiffscaled < 0.0 && ynextdiffscaled > 0.0 && yprevdiffscaled > 0.0) )  {
                                Point *newpt;
                                newpt = g_new0 (Point, 1);
                                newpt->x = BADPTVAL;