fixed bug reported by Geoff Bailey (acosh, asinh and atanh swap the precisions

of their inputs)


git-svn-id: svn://scm.gforge.inria.fr/svn/mpc/trunk@723 211d60ee-9f03-0410-a15a-8952a2c7a4e4

1 files changed, 18 insertions, 8 deletions

diff --git a/src/asinh.c b/src/asinh.c
index 4b67f9e..09c2ac7 100644
--- a/src/asinh.c
+++ b/src/asinh.c
@@ -1,6 +1,6 @@
 /* mpc_asinh -- inverse hyperbolic sine of a complex number.
 
-Copyright (C) 2009 Philippe Th\'eveny
+Copyright (C) 2009 Philippe Th\'eveny, Paul Zimmermann
 
 This file is part of the MPC Library.
 
@@ -26,21 +26,31 @@ mpc_asinh (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
 {
   /* asinh(op) = -i*asin(i*op) */
   int inex;
-  mpc_t z;
+  mpc_t z, a;
   mpfr_t tmp;
 
+  /* z = i*op */
   MPC_RE (z)[0] = MPC_IM (op)[0];
   MPC_IM (z)[0] = MPC_RE (op)[0];
   MPFR_CHANGE_SIGN (MPC_RE (z));
 
-  inex = mpc_asin (rop, z,
+  /* Note reversal of precisions due to later multiplication by -i */
+  mpc_init3 (a, MPC_PREC_IM(rop), MPC_PREC_RE(rop));
+
+  inex = mpc_asin (a, z,
                    RNDC (INV_RND (MPC_RND_IM (rnd)), MPC_RND_RE (rnd)));
 
-  /* change rop to -i*rop */
-  tmp[0] = MPC_RE (rop)[0];
-  MPC_RE (rop)[0] = MPC_IM (rop)[0];
-  MPC_IM (rop)[0] = tmp[0];
-  MPFR_CHANGE_SIGN (MPC_IM (rop));
+  /* if a = asin(i*op) = x+i*y, and we want y-i*x */
+
+  /* change a to -i*a */
+  tmp[0] = MPC_RE (a)[0];
+  MPC_RE (a)[0] = MPC_IM (a)[0];
+  MPC_IM (a)[0] = tmp[0];
+  MPFR_CHANGE_SIGN (MPC_IM (a));
+
+  mpc_set (rop, a, MPC_RNDNN);   /* exact */
+
+  mpc_clear (a);
 
   return MPC_INEX (MPC_INEX_IM (inex), -MPC_INEX_RE (inex));
 }