1 files changed, 52 insertions, 0 deletions
diff --git a/mpc/src/atanh.c b/mpc/src/atanh.c
new file mode 100644
index 0000000000..e5716cc703
--- /dev/null
+++ b/mpc/src/atanh.c
@@ -0,0 +1,52 @@
+/* mpc_atanh -- inverse hyperbolic tangent of a complex number.
+
+Copyright (C) 2009, 2011, 2012 INRIA
+
+This file is part of GNU MPC.
+
+GNU MPC 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.
+
+GNU MPC 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 this program. If not, see http://www.gnu.org/licenses/ .
+*/
+
+#include "mpc-impl.h"
+
+int
+mpc_atanh (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
+{
+  /* atanh(op) = -i*atan(i*op) */
+  int inex;
+  mpfr_t tmp;
+  mpc_t z, a;
+
+  mpc_realref (z)[0] = mpc_imagref (op)[0];
+  mpc_imagref (z)[0] = mpc_realref (op)[0];
+  MPFR_CHANGE_SIGN (mpc_realref (z));
+
+  /* Note reversal of precisions due to later multiplication by -i */
+  mpc_init3 (a, MPC_PREC_IM(rop), MPC_PREC_RE(rop));
+
+  inex = mpc_atan (a, z,
+                   MPC_RND (INV_RND (MPC_RND_IM (rnd)), MPC_RND_RE (rnd)));
+
+  /* change a to -i*a, i.e., x+i*y to y-i*x */
+  tmp[0] = mpc_realref (a)[0];
+  mpc_realref (a)[0] = mpc_imagref (a)[0];
+  mpc_imagref (a)[0] = tmp[0];
+  MPFR_CHANGE_SIGN (mpc_imagref (a));
+
+  mpc_set (rop, a, rnd);
+
+  mpc_clear (a);
+
+  return MPC_INEX (MPC_INEX_IM (inex), -MPC_INEX_RE (inex));
+}