1 files changed, 73 insertions, 0 deletions
diff --git a/mpfr/src/reldiff.c b/mpfr/src/reldiff.c
new file mode 100644
index 0000000000..a82400ef33
--- /dev/null
+++ b/mpfr/src/reldiff.c
@@ -0,0 +1,73 @@
+/* mpfr_reldiff -- compute relative difference of two floating-point numbers.
+
+Copyright 2000, 2001, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
+Contributed by the AriC and Caramel projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MPFR Library 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+/* reldiff(b, c) = abs(b-c)/b */
+void
+mpfr_reldiff (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
+{
+  mpfr_t b_copy;
+
+  if (MPFR_ARE_SINGULAR (b, c))
+    {
+      if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c))
+        {
+          MPFR_SET_NAN(a);
+          return;
+        }
+      else if (MPFR_IS_INF(b))
+        {
+          if (MPFR_IS_INF (c) && (MPFR_SIGN (c) == MPFR_SIGN (b)))
+            MPFR_SET_ZERO(a);
+          else
+            MPFR_SET_NAN(a);
+          return;
+        }
+      else if (MPFR_IS_INF(c))
+        {
+          MPFR_SET_SAME_SIGN (a, b);
+          MPFR_SET_INF (a);
+          return;
+        }
+      else if (MPFR_IS_ZERO(b)) /* reldiff = abs(c)/c = sign(c) */
+        {
+          mpfr_set_si (a, MPFR_INT_SIGN (c), rnd_mode);
+          return;
+        }
+      /* Fall through */
+    }
+
+  if (a == b)
+    {
+      mpfr_init2 (b_copy, MPFR_PREC(b));
+      mpfr_set (b_copy, b, MPFR_RNDN);
+    }
+
+  mpfr_sub (a, b, c, rnd_mode);
+  mpfr_abs (a, a, rnd_mode); /* for compatibility with MPF */
+  mpfr_div (a, a, (a == b) ? b_copy : b, rnd_mode);
+
+  if (a == b)
+    mpfr_clear (b_copy);
+
+}