Added new files resulting from directory restructuring.

[pspp-builds.git] / src / math / histogram.c

diff --git a/src/math/histogram.c b/src/math/histogram.c
new file mode 100644 (file)
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+++ b/src/math/histogram.c
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+/* PSPP - computes sample statistics.
+   Copyright (C) 2004 Free Software Foundation, Inc.
+   Written by John Darrington <john@darrington.wattle.id.au>
+
+   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 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. */
+
+#include <config.h>
+#include <math.h>
+#include <gsl/gsl_histogram.h>
+#include <assert.h>
+#include "histogram.h"
+#include "chart-geometry.h"
+
+
+gsl_histogram *
+histogram_create(double bins, double x_min, double x_max)
+{
+  int n;
+  double bin_width ;
+  double bin_width_2 ;
+  double upper_limit, lower_limit;
+
+  gsl_histogram *hist = gsl_histogram_alloc(bins);
+
+  bin_width = chart_rounded_tick((x_max - x_min)/ bins);
+  bin_width_2 = bin_width / 2.0;
+    
+  n =  ceil( x_max / (bin_width_2) ) ; 
+  if ( ! (n % 2 ) ) n++;
+  upper_limit = n * bin_width_2;
+
+  n =  floor( x_min / (bin_width_2) ) ; 
+  if ( ! (n % 2 ) ) n--;
+  lower_limit = n * bin_width_2;
+
+  gsl_histogram_set_ranges_uniform(hist, lower_limit, upper_limit);
+
+  return hist;
+}
+