[gnumeric] sstest: test also negative binomial distribution.

[Morten Welinder <mortenw src gnome org>]

commit ec0c8b857a33fab81eed79b58c2272fb8f82b753
Author: Morten Welinder <terra gnome org>
Date:   Fri Mar 20 09:24:54 2015 -0400

    sstest: test also negative binomial distribution.

 ChangeLog    |    1 +
 src/sstest.c |   71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 71 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 1fbdfaf..8e5dc6a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,7 @@
        (test_random_randexp): New test.
        (test_random_randpoisson): New test.
        (test_random_randgeom): New test.
+       (test_random_randnegbinom): New test.
 
        * src/gnm-random.c (random_logarithmic): Fix.  See #746449.
 
diff --git a/src/sstest.c b/src/sstest.c
index 2e5c51a..0a5cb51 100644
--- a/src/sstest.c
+++ b/src/sstest.c
@@ -1002,6 +1002,75 @@ test_random_randbinom (int N)
 }
 
 static void
+test_random_randnegbinom (int N)
+{
+       gnm_float mean, var, skew, kurt;
+       gnm_float *vals;
+       gboolean ok;
+       gnm_float param_p = random_01 ();
+       gnm_float param_fails = gnm_floor (1 / (0.0001 + gnm_pow (random_01 (), 4)));
+       /* Warning: these differ from Wikipedia by swapping p and 1-p.  */
+       gnm_float mean_target = param_fails * (1 - param_p) / param_p;
+       gnm_float var_target = mean_target / param_p;
+       gnm_float skew_target = (2 - param_p) / gnm_sqrt (param_fails * (1 - param_p));
+       gnm_float kurt_target = 6 / param_fails + 1 / var_target;
+       char *expr;
+       gnm_float T;
+       int i;
+
+       expr = g_strdup_printf ("=RANDNEGBINOM(%.10" GNM_FORMAT_g ",%.0" GNM_FORMAT_f ")", param_p, 
param_fails);
+       vals = test_random_1 (N, expr, &mean, &var, &skew, &kurt);
+       g_free (expr);
+
+       ok = TRUE;
+       for (i = 0; i < N; i++) {
+               gnm_float r = vals[i];
+               if (!(r >= 0 && gnm_finite (r) && r == gnm_floor (r))) {
+                       g_printerr ("Range failure.\n");
+                       ok = FALSE;
+                       break;
+               }
+       }
+       g_free (vals);
+
+       T = mean_target;
+       g_printerr ("Expected mean: %.10" GNM_FORMAT_g "\n", T);
+       if (!(T >= 0 && gnm_finite (T))) {
+               /* That is a very simplistic test! */
+               g_printerr ("Mean failure.\n");
+               ok = FALSE;
+       }
+
+       T = var_target;
+       g_printerr ("Expected var: %.10" GNM_FORMAT_g "\n", T);
+       if (!(T >= 0 && gnm_finite (T))) {
+               /* That is a very simplistic test! */
+               g_printerr ("Var failure.\n");
+               ok = FALSE;
+       }
+
+       T = skew_target;
+       g_printerr ("Expected skew: %.10" GNM_FORMAT_g "\n", T);
+       if (!gnm_finite (T)) {
+               /* That is a very simplistic test! */
+               g_printerr ("Skew failure.\n");
+               ok = FALSE;
+       }
+
+       T = kurt_target;
+       g_printerr ("Expected kurt: %.10" GNM_FORMAT_g "\n", T);
+       if (!(T >= -3 && gnm_finite (T))) {
+               /* That is a very simplistic test! */
+               g_printerr ("Kurt failure.\n");
+               ok = FALSE;
+       }
+
+       if (ok)
+               g_printerr ("OK\n");
+       g_printerr ("\n");
+}
+
+static void
 test_random_randbetween (int N)
 {
        gnm_float mean, var, skew, kurt;
@@ -1221,6 +1290,7 @@ test_random (void)
 
         test_random_randbernoulli (N);
         test_random_randbinom (N);
+        test_random_randnegbinom (N);
         test_random_randbetween (N);
         test_random_randpoisson (N);
         test_random_randgeom (N);
@@ -1242,7 +1312,6 @@ test_random (void)
         test_random_randlog (N);
         test_random_randlogistic (N);
         test_random_randlognorm (N);
-        test_random_randnegbinom (N);
         test_random_randpareto (N);
         test_random_randrayleigh (N);
         test_random_randrayleightail (N);