New module to perform decimal floating point arithmetic for charts.

[pspp] / src / output / charts / plot-hist-cairo.c

diff --git a/src/output/charts/plot-hist-cairo.c b/src/output/charts/plot-hist-cairo.c
index a9a5d44f58b475aef164f8fe9077008d4264ece8..006b39225e274f73e7d0dd2241a203ff7143d25c 100644 (file)
--- a/src/output/charts/plot-hist-cairo.c
+++ b/src/output/charts/plot-hist-cairo.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2009, 2011 Free Software Foundation, Inc.
+   Copyright (C) 2009, 2011, 2014 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
@@ -15,9 +15,10 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-
+#include "math/decimal.h"
 #include "output/charts/plot-hist.h"
 
+#include <float.h>
 #include <gsl/gsl_randist.h>
 
 #include "data/val-type.h"
@@ -102,8 +103,20 @@ hist_draw_bar (cairo_t *cr, const struct xrchart_geometry *geom,
   cairo_stroke (cr);
 
   if (label)
-    draw_tick (cr, geom, SCALE_ABSCISSA, bins > 10,
-              x_pos + width / 2.0, "%g", (upper + lower) / 2.0);
+    {
+      struct decimal decupper;
+      struct decimal declower;
+      struct decimal middle;
+      decimal_from_double (&declower, lower);
+      decimal_from_double (&decupper, upper);
+      middle = declower;
+      decimal_add (&middle, &decupper);
+      decimal_int_divide (&middle, 2);
+      char *str = decimal_to_string (&middle);
+      draw_tick (cr, geom, SCALE_ABSCISSA, bins > 10,
+                x_pos + width / 2.0, "%s", str);
+      free (str);
+    }
 }
 
 void
@@ -127,7 +140,7 @@ xrchart_draw_histogram (const struct chart_item *chart_item, cairo_t *cr,
 
   bins = gsl_histogram_bins (h->gsl_hist);
 
-  xrchart_write_yscale (cr, geom, 0, gsl_histogram_max_val (h->gsl_hist), 5);
+  xrchart_write_yscale (cr, geom, 0, gsl_histogram_max_val (h->gsl_hist));
 
   for (i = 0; i < bins; i++)
     {