1 files changed, 77 insertions, 0 deletions
diff --git a/src/expo.c b/src/expo.c
new file mode 100644
index 0000000..3af8629
--- /dev/null
+++ b/src/expo.c
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+/* ---------------------------- rand_expo ------------------------------------- */
+/*                                                                              */
+/* rand_expo generates a exponentially distributed random variable.             */
+/* Written by Olaf Matthes (olaf.matthes@gmx.de)                                */
+/* Based on code found in Dodge/Jerse "Computer Music"                          */
+/* Get source at http://www.akustische-kunst.org/puredata/maxlib/               */
+/*                                                                              */
+/* 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.  */
+/*                                                                              */
+/* Based on PureData by Miller Puckette and others.                             */
+/*                                                                              */
+/* ---------------------------------------------------------------------------- */
+
+#include "m_pd.h"
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+
+#define fran()         (t_float)rand()/(t_float)RAND_MAX
+
+static char *version = "expo v0.1, generates exponentially distributed random variable\n"
+                       "           written by Olaf Matthes <olaf.matthes@gmx.de>";
+
+/* -------------------------- rand_expo ------------------------------ */
+
+static t_class *rand_expo_class;
+
+typedef struct _rand_expo
+{
+    t_object x_obj;
+	t_float  x_lambda;
+} t_rand_expo;
+
+static void *rand_expo_new(t_floatarg f)
+{
+    t_rand_expo *x = (t_rand_expo *)pd_new(rand_expo_class);
+    srand( (unsigned)time( NULL ) );
+    floatinlet_new(&x->x_obj, &x->x_lambda);
+    outlet_new(&x->x_obj, &s_float);
+	x->x_lambda = f;
+    return (x);
+}
+
+static void rand_expo_bang(t_rand_expo *x)
+{
+	t_float u, l;
+	l = (x->x_lambda <= 0 ? 0.0001 : x->x_lambda);
+	do
+	{
+		u = fran();
+	}
+	while(u == 0);
+    outlet_float(x->x_obj.ob_outlet, -log(u)/l);
+}
+
+void expo_setup(void)
+{
+    rand_expo_class = class_new(gensym("expo"), (t_newmethod)rand_expo_new, 0,
+    	sizeof(t_rand_expo), 0, A_DEFFLOAT, 0);
+    class_addbang(rand_expo_class, rand_expo_bang);
+	class_sethelpsymbol(rand_expo_class, gensym("maxlib/help-expo.pd"));
+#ifndef MAXLIB
+    post(version);
+#endif
+}