1 /* mpc_mul_i -- Multiply a complex number by plus or minus i.
2
3 Copyright (C) 2005, 2009, 2010, 2011 INRIA
4
5 This file is part of GNU MPC.
6
7 GNU MPC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU Lesser General Public License as published by the
9 Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
11
12 GNU MPC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
15 more details.
16
17 You should have received a copy of the GNU Lesser General Public License
18 along with this program. If not, see http://www.gnu.org/licenses/ .
19 */
20
21 #include "mpc-impl.h"
22
23 int
mpc_mul_i(mpc_ptr a,mpc_srcptr b,int sign,mpc_rnd_t rnd)24 mpc_mul_i (mpc_ptr a, mpc_srcptr b, int sign, mpc_rnd_t rnd)
25 /* if sign is >= 0, multiply by i, otherwise by -i */
26 {
27 int inex_re, inex_im;
28 mpfr_t tmp;
29
30 /* Treat the most probable case of compatible precisions first */
31 if ( MPC_PREC_RE (b) == MPC_PREC_IM (a)
32 && MPC_PREC_IM (b) == MPC_PREC_RE (a))
33 {
34 if (a == b)
35 mpfr_swap (mpc_realref (a), mpc_imagref (a));
36 else
37 {
38 mpfr_set (mpc_realref (a), mpc_imagref (b), GMP_RNDN);
39 mpfr_set (mpc_imagref (a), mpc_realref (b), GMP_RNDN);
40 }
41 if (sign >= 0)
42 MPFR_CHANGE_SIGN (mpc_realref (a));
43 else
44 MPFR_CHANGE_SIGN (mpc_imagref (a));
45 inex_re = 0;
46 inex_im = 0;
47 }
48 else
49 {
50 if (a == b)
51 {
52 mpfr_init2 (tmp, MPC_PREC_RE (a));
53 if (sign >= 0)
54 {
55 inex_re = mpfr_neg (tmp, mpc_imagref (b), MPC_RND_RE (rnd));
56 inex_im = mpfr_set (mpc_imagref (a), mpc_realref (b), MPC_RND_IM (rnd));
57 }
58 else
59 {
60 inex_re = mpfr_set (tmp, mpc_imagref (b), MPC_RND_RE (rnd));
61 inex_im = mpfr_neg (mpc_imagref (a), mpc_realref (b), MPC_RND_IM (rnd));
62 }
63 mpfr_clear (mpc_realref (a));
64 mpc_realref (a)[0] = tmp [0];
65 }
66 else
67 if (sign >= 0)
68 {
69 inex_re = mpfr_neg (mpc_realref (a), mpc_imagref (b), MPC_RND_RE (rnd));
70 inex_im = mpfr_set (mpc_imagref (a), mpc_realref (b), MPC_RND_IM (rnd));
71 }
72 else
73 {
74 inex_re = mpfr_set (mpc_realref (a), mpc_imagref (b), MPC_RND_RE (rnd));
75 inex_im = mpfr_neg (mpc_imagref (a), mpc_realref (b), MPC_RND_IM (rnd));
76 }
77 }
78
79 return MPC_INEX(inex_re, inex_im);
80 }
81