1 /* mpc_cmp -- Compare two complex numbers.
2
3 Copyright (C) 2016 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 /* return mpfr_cmp (mpc_abs (a), mpc_abs (b)) */
24 int
mpc_cmp_abs(mpc_srcptr a,mpc_srcptr b)25 mpc_cmp_abs (mpc_srcptr a, mpc_srcptr b)
26 {
27 mpc_t z1, z2;
28 mpfr_t n1, n2;
29 mpfr_prec_t prec;
30 int inex1, inex2, ret;
31
32 /* Handle numbers containing one NaN as mpfr_cmp. */
33 if ( mpfr_nan_p (mpc_realref (a)) || mpfr_nan_p (mpc_imagref (a))
34 || mpfr_nan_p (mpc_realref (b)) || mpfr_nan_p (mpc_imagref (b)))
35 {
36 mpfr_t nan;
37 mpfr_init (nan);
38 mpfr_set_nan (nan);
39 ret = mpfr_cmp (nan, nan);
40 mpfr_clear (nan);
41 return ret;
42 }
43
44 /* Handle infinities. */
45 if (mpc_inf_p (a))
46 if (mpc_inf_p (b))
47 return 0;
48 else
49 return 1;
50 else if (mpc_inf_p (b))
51 return -1;
52
53 /* Replace all parts of a and b by their absolute values, then order
54 them by size. */
55 z1 [0] = a [0];
56 z2 [0] = b [0];
57 if (mpfr_signbit (mpc_realref (a)))
58 MPFR_CHANGE_SIGN (mpc_realref (z1));
59 if (mpfr_signbit (mpc_imagref (a)))
60 MPFR_CHANGE_SIGN (mpc_imagref (z1));
61 if (mpfr_signbit (mpc_realref (b)))
62 MPFR_CHANGE_SIGN (mpc_realref (z2));
63 if (mpfr_signbit (mpc_imagref (b)))
64 MPFR_CHANGE_SIGN (mpc_imagref (z2));
65 if (mpfr_cmp (mpc_realref (z1), mpc_imagref (z1)) > 0)
66 mpfr_swap (mpc_realref (z1), mpc_imagref (z1));
67 if (mpfr_cmp (mpc_realref (z2), mpc_imagref (z2)) > 0)
68 mpfr_swap (mpc_realref (z2), mpc_imagref (z2));
69
70 /* Handle cases in which only one part differs. */
71 if (mpfr_cmp (mpc_realref (z1), mpc_realref (z2)) == 0)
72 return mpfr_cmp (mpc_imagref (z1), mpc_imagref (z2));
73 if (mpfr_cmp (mpc_imagref (z1), mpc_imagref (z2)) == 0)
74 return mpfr_cmp (mpc_realref (z1), mpc_realref (z2));
75
76 /* Implement the algorithm in algorithms.tex. */
77 mpfr_init (n1);
78 mpfr_init (n2);
79 prec = MPC_MAX (50, MPC_MAX (MPC_MAX_PREC (z1), MPC_MAX_PREC (z2)) / 100);
80 do {
81 mpfr_set_prec (n1, prec);
82 mpfr_set_prec (n2, prec);
83 inex1 = mpc_norm (n1, z1, MPFR_RNDD);
84 inex2 = mpc_norm (n2, z2, MPFR_RNDD);
85 ret = mpfr_cmp (n1, n2);
86 if (ret != 0)
87 goto end;
88 else
89 if (inex1 == 0) /* n1 = norm(z1) */
90 if (inex2) /* n2 < norm(z2) */
91 {
92 ret = -1;
93 goto end;
94 }
95 else /* n2 = norm(z2) */
96 {
97 ret = 0;
98 goto end;
99 }
100 else /* n1 < norm(z1) */
101 if (inex2 == 0)
102 {
103 ret = 1;
104 goto end;
105 }
106 prec *= 2;
107 } while (1);
108 end:
109 mpfr_clear (n1);
110 mpfr_clear (n2);
111 return ret;
112 }
113
114