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 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   6 .\" Distributed under GPL
   7 .\" %%%LICENSE_END
   8 .\"
   9 .TH SINCOS 3  2017-09-15 "GNU" "Linux Programmer's Manual"
  10 .SH NAME
  11 sincos, sincosf, sincosl \- calculate sin and cos simultaneously
  12 .SH SYNOPSIS
  13 .nf
  14 .BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
  15 .B #include <math.h>
  16 .PP
  17 .BI "void sincos(double " x ", double *" sin ", double *" cos );
  18 .BI "void sincosf(float " x ", float *" sin ", float *" cos );
  19 .BI "void sincosl(long double " x ", long double *" sin ", long double *" cos );
  20 .fi
  21 .PP
  22 Link with \fI\-lm\fP.
  23 .SH DESCRIPTION
  24 Several applications need sine and cosine of the same angle
  25 .IR x .
  26 These functions compute both at the same time, and store the results in
  27 .I *sin
  28 and
  29 .IR *cos .
  30 Using this function can be more efficient than two separate calls to
  31 .BR sin (3)
  32 and
  33 .BR cos (3).
  34 .PP
  35 If
  36 .I x
  37 is a NaN,
  38 a NaN is returned in
  39 .I *sin
  40 and
  41 .IR *cos .
  42 .PP
  43 If
  44 .I x
  45 is positive infinity or negative infinity,
  46 a domain error occurs, and
  47 a NaN is returned in
  48 .I *sin
  49 and
  50 .IR *cos .
  51 .SH RETURN VALUE
  52 These functions return
  53 .IR void .
  54 .SH ERRORS
  55 See
  56 .BR math_error (7)
  57 for information on how to determine whether an error has occurred
  58 when calling these functions.
  59 .PP
  60 The following errors can occur:
  61 .TP
  62 Domain error: \fIx\fP is an infinity
  63 .\" .I errno
  64 .\" is set to
  65 .\" .BR EDOM .
  66 An invalid floating-point exception
  67 .RB ( FE_INVALID )
  68 is raised.
  69 .PP
  70 These functions do not set
  71 .IR errno .
  72 .\" FIXME . Is it intentional that these functions do not set errno?
  73 .\" sin() and cos() also don't set errno; bugs have been raised for
  74 .\" those functions.
  75 .\" See https://www.sourceware.org/bugzilla/show_bug.cgi?id=15467
  76 .SH VERSIONS
  77 These functions first appeared in glibc in version 2.1.
  78 .SH ATTRIBUTES
  79 For an explanation of the terms used in this section, see
  80 .BR attributes (7).
  81 .TS
  82 allbox;
  83 lbw30 lb lb
  84 l l l.
  85 Interface       Attribute       Value
  86 T{
  87 .BR sincos (),
  88 .BR sincosf (),
  89 .BR sincosl ()
  90 T}      Thread safety   MT-Safe
  91 .TE
  92 .SH CONFORMING TO
  93 These functions are GNU extensions.
  94 .SH NOTES
  95 To see the performance advantage of
  96 .BR sincos (),
  97 it may be necessary to disable
  98 .BR gcc (1)
  99 builtin optimizations, using flags such as:
 100 .PP
 101 .in +4n
 102 .EX
 103 cc -O \-lm \-fno\-builtin prog.c
 104 .EE
 105 .in
 106 .SH SEE ALSO
 107 .BR cos (3),
 108 .BR sin (3),
 109 .BR tan (3)