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fea681da | 1 | .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de) |
2297bf0e | 2 | .\" |
38f20bb9 | 3 | .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE) |
fea681da | 4 | .\" Distributed under GPL |
38f20bb9 | 5 | .\" %%%LICENSE_END |
fea681da | 6 | .\" |
4b8c67d9 | 7 | .TH CARG 3 2017-09-15 "" "Linux Programmer's Manual" |
fea681da | 8 | .SH NAME |
09a15e3d | 9 | carg, cargf, cargl \- calculate the complex argument |
fea681da MK |
10 | .SH SYNOPSIS |
11 | .B #include <complex.h> | |
68e4db0a | 12 | .PP |
fea681da | 13 | .BI "double carg(double complex " z ");" |
d39541ec | 14 | .br |
fea681da | 15 | .BI "float cargf(float complex " z ");" |
d39541ec | 16 | .br |
fea681da | 17 | .BI "long double cargl(long double complex " z ");" |
68e4db0a | 18 | .PP |
20c58d70 | 19 | Link with \fI\-lm\fP. |
fea681da | 20 | .SH DESCRIPTION |
8fd531f3 MK |
21 | These functions calculate the complex argument (also called phase angle) of |
22 | .IR z , | |
23 | with a branch cut along the negative real axis. | |
847e0d88 | 24 | .PP |
fea681da | 25 | A complex number can be described by two real coordinates. |
daac0b39 | 26 | One may use rectangular coordinates and gets |
847e0d88 | 27 | .PP |
daac0b39 MK |
28 | .nf |
29 | z = x + I * y | |
30 | .fi | |
847e0d88 | 31 | .PP |
c6fa0841 MK |
32 | where |
33 | .IR "x\ =\ creal(z)" | |
34 | and | |
35 | .IR "y\ =\ cimag(z)" . | |
dd3568a1 | 36 | .PP |
daac0b39 | 37 | Or one may use polar coordinates and gets |
207050fa | 38 | .PP |
daac0b39 | 39 | .nf |
daac0b39 | 40 | z = r * cexp(I * a) |
daac0b39 | 41 | .fi |
207050fa | 42 | .PP |
c6fa0841 MK |
43 | where |
44 | .IR "r\ =\ cabs(z)" | |
45 | is the "radius", the "modulus", the absolute value of | |
46 | .IR z , | |
47 | and | |
48 | .IR "a\ =\ carg(z)" | |
49 | is the "phase angle", the argument of | |
50 | .IR z . | |
dd3568a1 | 51 | .PP |
daac0b39 | 52 | One has: |
207050fa | 53 | .PP |
daac0b39 | 54 | .nf |
daac0b39 MK |
55 | tan(carg(z)) = cimag(z) / creal(z) |
56 | .fi | |
47297adb | 57 | .SH RETURN VALUE |
8c383102 | 58 | The return value is the range of [\-pi,pi]. |
f0d7ce1d MK |
59 | .SH VERSIONS |
60 | These functions first appeared in glibc in version 2.1. | |
4906e3f0 MS |
61 | .SH ATTRIBUTES |
62 | For an explanation of the terms used in this section, see | |
63 | .BR attributes (7). | |
64 | .TS | |
65 | allbox; | |
66 | lbw24 lb lb | |
67 | l l l. | |
68 | Interface Attribute Value | |
69 | T{ | |
70 | .BR carg (), | |
71 | .BR cargf (), | |
72 | .BR cargl () | |
73 | T} Thread safety MT-Safe | |
74 | .TE | |
47297adb | 75 | .SH CONFORMING TO |
9a74e018 | 76 | C99, POSIX.1-2001, POSIX.1-2008. |
47297adb | 77 | .SH SEE ALSO |
fea681da | 78 | .BR cabs (3), |
a8bda636 | 79 | .BR complex (7) |