man3/sincos.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
   3 .\"     <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: GPL-1.0-or-later
   6 .\"
   7 .TH SINCOS 3  2021-03-22 "GNU" "Linux Programmer's Manual"
   8 .SH NAME
   9 sincos, sincosf, sincosl \- calculate sin and cos simultaneously
  10 .SH LIBRARY
  11 Math library
  12 .RI ( libm ", " \-lm )
  13 .SH SYNOPSIS
  14 .nf
  15 .BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
  16 .B #include <math.h>
  17 .PP
  18 .BI "void sincos(double " x ", double *" sin ", double *" cos );
  19 .BI "void sincosf(float " x ", float *" sin ", float *" cos );
  20 .BI "void sincosl(long double " x ", long double *" sin ", long double *" cos );
  21 .fi
  22 .SH DESCRIPTION
  23 Several applications need sine and cosine of the same angle
  24 .IR x .
  25 These functions compute both at the same time, and store the results in
  26 .I *sin
  27 and
  28 .IR *cos .
  29 Using this function can be more efficient than two separate calls to
  30 .BR sin (3)
  31 and
  32 .BR cos (3).
  33 .PP
  34 If
  35 .I x
  36 is a NaN,
  37 a NaN is returned in
  38 .I *sin
  39 and
  40 .IR *cos .
  41 .PP
  42 If
  43 .I x
  44 is positive infinity or negative infinity,
  45 a domain error occurs, and
  46 a NaN is returned in
  47 .I *sin
  48 and
  49 .IR *cos .
  50 .SH RETURN VALUE
  51 These functions return
  52 .IR void .
  53 .SH ERRORS
  54 See
  55 .BR math_error (7)
  56 for information on how to determine whether an error has occurred
  57 when calling these functions.
  58 .PP
  59 The following errors can occur:
  60 .TP
  61 Domain error: \fIx\fP is an infinity
  62 .I errno
  63 is set to
  64 .BR EDOM
  65 (but see BUGS).
  66 An invalid floating-point exception
  67 .RB ( FE_INVALID )
  68 is raised.
  69 .SH VERSIONS
  70 These functions first appeared in glibc in version 2.1.
  71 .SH ATTRIBUTES
  72 For an explanation of the terms used in this section, see
  73 .BR attributes (7).
  74 .ad l
  75 .nh
  76 .TS
  77 allbox;
  78 lbx lb lb
  79 l l l.
  80 Interface       Attribute       Value
  81 T{
  82 .BR sincos (),
  83 .BR sincosf (),
  84 .BR sincosl ()
  85 T}      Thread safety   MT-Safe
  86 .TE
  87 .hy
  88 .ad
  89 .sp 1
  90 .SH CONFORMING TO
  91 These functions are GNU extensions.
  92 .SH NOTES
  93 To see the performance advantage of
  94 .BR sincos (),
  95 it may be necessary to disable
  96 .BR gcc (1)
  97 built-in optimizations, using flags such as:
  98 .PP
  99 .in +4n
 100 .EX
 101 cc \-O \-lm \-fno\-builtin prog.c
 102 .EE
 103 .in
 104 .SH BUGS
 105 Before version 2.22, the glibc implementation did not set
 106 .\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=15467
 107 .I errno
 108 to
 109 .B EDOM
 110 when a domain error occurred.
 111 .SH SEE ALSO
 112 .BR cos (3),
 113 .BR sin (3),
 114 .BR tan (3)