diff -Naur mpfr-2.1.0-p6/sum.c mpfr-2.1.0-p7/sum.c
--- mpfr-2.1.0-p6/sum.c	2004-02-24 13:23:35.000000000 +0000
+++ mpfr-2.1.0-p7/sum.c	2005-01-23 23:19:18.010431168 +0000
@@ -1,6 +1,6 @@
 /* Sum -- efficiently sum a list of floating-point numbers
 
-Copyright 2004 Free Software Foundation, Inc.
+Copyright 2004, 2005 Free Software Foundation, Inc.
 
 This file is part of the MPFR Library.
 
@@ -169,17 +169,18 @@
 {
   unsigned long i;
   mpfr_t sum;
-  int error_trap = 0;
+  int error_trap;
+
+  if (MPFR_UNLIKELY (n == 1))
+    return mpfr_set (ret, tab[0], GMP_RNDN);
 
   mpfr_init2 (sum, F);
-  mpfr_set (sum, tab[0], GMP_RNDN);
 
+  error_trap = mpfr_set (sum, tab[0], GMP_RNDN);
   for (i = 1; i < n - 1; i++)
-    {
-      error_trap |= mpfr_add (sum, sum, tab[i], GMP_RNDN);
-    }
-
+    error_trap |= mpfr_add (sum, sum, tab[i], GMP_RNDN);
   error_trap |= mpfr_add (ret, sum, tab[n - 1], GMP_RNDN);
+
   mpfr_clear (sum);
   return error_trap;
 }
@@ -201,6 +202,11 @@
   TMP_DECL(marker);
     
   TMP_MARK(marker);
+  if (MPFR_UNLIKELY (n == 0)) {
+    MPFR_SET_ZERO (ret);
+    MPFR_SET_POS (ret);
+    return 0;
+  }
 
   perm = (mpfr_srcptr *) TMP_ALLOC(n * sizeof(mpfr_srcptr));