fish: Implement progress bars in guestfish.

[libguestfs.git] / fish / rmsd.h

diff --git a/fish/rmsd.h b/fish/rmsd.h
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+++ b/fish/rmsd.h
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+/* libguestfs - guestfish shell
+ * Copyright (C) 2010 Red Hat 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 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.
+ */
+
+#ifndef FISH_RMSD_H
+#define FISH_RMSD_H
+
+/* Compute the running mean and standard deviation from the
+ * series of estimated values.
+ *
+ * Method:
+ * http://en.wikipedia.org/wiki/Standard_deviation#Rapid_calculation_methods
+ * Checked in a test program against answers given by Wolfram Alpha.
+ */
+struct rmsd {
+  double a;                     /* mean */
+  double i;                     /* number of samples */
+  double q;
+};
+
+static void
+rmsd_init (struct rmsd *r)
+{
+  r->a = 0;
+  r->i = 1;
+  r->q = 0;
+}
+
+static void
+rmsd_add_sample (struct rmsd *r, double x)
+{
+  double a_next, q_next;
+
+  a_next = r->a + (x - r->a) / r->i;
+  q_next = r->q + (x - r->a) * (x - a_next);
+  r->a = a_next;
+  r->q = q_next;
+  r->i += 1.0;
+}
+
+static double
+rmsd_get_mean (const struct rmsd *r)
+{
+  return r->a;
+}
+
+static double
+rmsd_get_standard_deviation (const struct rmsd *r)
+{
+  return sqrt (r->q / (r->i - 1.0));
+}
+
+#endif /* FISH_RMSD_H */