Merge 'master' into 'psppsheet'.

[pspp] / src / math / chart-geometry.c

diff --git a/src/math/chart-geometry.c b/src/math/chart-geometry.c
index 0f6da46edefd0c2fd0d93162b42344ddd7ebd85d..eb0ad9282a854885768472319a899dbfba6c14ea 100644 (file)
--- a/src/math/chart-geometry.c
+++ b/src/math/chart-geometry.c
@@ -1,20 +1,18 @@
-/* PSPP - computes sample statistics.
+/* PSPP - a program for statistical analysis.
    Copyright (C) 2004 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or
-   modify it under the terms of the GNU General Public License as
-   published by the Free Software Foundation; either version 2 of the
-   License, or (at your option) any later version.
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   This program is distributed in the hope that it will be useful, but
-   WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   General Public License for more details.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-   02110-1301, USA. */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
 #include <math.h>
@@ -22,26 +20,32 @@
 
 #include "chart-geometry.h"
 
-/* Adjust tick to be a sensible value 
+static const double standard_ticks[] = {1, 2, 5, 10};
+
+
+/* Adjust tick to be a sensible value
    ie:  ... 0.1,0.2,0.5,   1,2,5,  10,20,50 ... */
 double
-chart_rounded_tick(double tick)
+chart_rounded_tick (double tick)
 {
-
   int i;
 
   double diff = DBL_MAX;
   double t = tick;
-    
-  static const double standard_ticks[] = {1, 2, 5, 10};
 
-  const double factor = pow(10,ceil(log10(standard_ticks[0] / tick))) ;
+  double factor;
+
+  /* Avoid arithmetic problems with very small values */
+  if (fabs (tick) < DBL_EPSILON)
+     return 0;
+
+  factor = pow (10,ceil (log10 (standard_ticks[0] / tick)));
 
-  for (i = 3  ; i >= 0 ; --i) 
+  for (i = 3  ; i >= 0 ; --i)
     {
-      const double d = fabs( tick - standard_ticks[i] / factor ) ;
+      const double d = fabs (tick - standard_ticks[i] / factor);
 
-      if ( d < diff ) 
+      if ( d < diff )
        {
          diff = d;
          t = standard_ticks[i] / factor ;
@@ -49,6 +53,5 @@ chart_rounded_tick(double tick)
     }
 
   return t;
-    
 }