From 989a193268b963aa1047814f7f1402084fb7d859 Mon Sep 17 00:00:00 2001
From: Patrick Alken <alken@colorado.edu>
Date: Sat, 16 Apr 2022 11:56:10 -0600
Subject: fix for bug #59624

---
 NEWS                          |  2 ++
 statistics/quantiles.c        |  1 +
 statistics/quantiles_source.c | 35 +++++++++++++++++++++--------------
 3 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/statistics/quantiles.c b/statistics/quantiles.c
index 96a3a25..50898d9 100644
--- a/statistics/quantiles.c
+++ b/statistics/quantiles.c
@@ -1,5 +1,6 @@
 #include <config.h>
 #include <gsl/gsl_statistics.h>
+#include <gsl/gsl_errno.h>
 
 #define BASE_LONG_DOUBLE
 #include "templates_on.h"
diff --git a/statistics/quantiles_source.c b/statistics/quantiles_source.c
index e2956d9..b2feba4 100644
--- a/statistics/quantiles_source.c
+++ b/statistics/quantiles_source.c
@@ -24,22 +24,29 @@ FUNCTION(gsl_stats,quantile_from_sorted_data) (const BASE sorted_data[],
                                                const size_t n,
                                                const double f)
 {
-  const double index = f * (n - 1) ;
-  const size_t lhs = (int)index ;
-  const double delta = index - lhs ;
-  double result;
-
-  if (n == 0)
-    return 0.0 ;
-
-  if (lhs == n - 1)
+  if ((f < 0.0) || (f > 1.0))
     {
-      result = sorted_data[lhs * stride] ;
+      GSL_ERROR_VAL ("invalid quantile fraction", GSL_EDOM, 0.0);
     }
-  else 
+  else
     {
-      result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ;
-    }
+      const double index = f * (n - 1) ;
+      const size_t lhs = (int)index ;
+      const double delta = index - lhs ;
+      double result;
 
-  return result ;
+      if (n == 0)
+        return 0.0 ;
+
+      if (lhs == n - 1)
+        {
+          result = sorted_data[lhs * stride] ;
+        }
+      else 
+        {
+          result = (1 - delta) * sorted_data[lhs * stride] + delta * sorted_data[(lhs + 1) * stride] ;
+        }
+
+      return result ;
+    }
 }
-- 
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