man3/csqrt.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   4 .\" Distributed under GPL
   5 .\" %%%LICENSE_END
   6 .\"
   7 .TH CSQRT 3 2017-09-15 "" "Linux Programmer's Manual"
   8 .SH NAME
   9 csqrt, csqrtf, csqrtl \- complex square root
  10 .SH SYNOPSIS
  11 .B #include <complex.h>
  12 .PP
  13 .BI "double complex csqrt(double complex " z ");"
  14 .br
  15 .BI "float complex csqrtf(float complex " z ");"
  16 .br
  17 .BI "long double complex csqrtl(long double complex " z ");"
  18 .PP
  19 Link with \fI\-lm\fP.
  20 .SH DESCRIPTION
  21 These functions calculate the complex square root of
  22 .IR z ,
  23 with a branch cut along the negative real axis.
  24 (That means that \fIcsqrt(\-1+eps*I)\fP will be close to I while
  25 \fIcsqrt(\-1\-eps*I)\fP will be close to \-I, \fIif eps\fP is a small positive
  26 real number.)
  27 .SH VERSIONS
  28 These functions first appeared in glibc in version 2.1.
  29 .SH ATTRIBUTES
  30 For an explanation of the terms used in this section, see
  31 .BR attributes (7).
  32 .TS
  33 allbox;
  34 lbw27 lb lb
  35 l l l.
  36 Interface       Attribute       Value
  37 T{
  38 .BR csqrt (),
  39 .BR csqrtf (),
  40 .BR csqrtl ()
  41 T}      Thread safety   MT-Safe
  42 .TE
  43 .sp 1
  44 .SH CONFORMING TO
  45 C99, POSIX.1-2001, POSIX.1-2008.
  46 .SH SEE ALSO
  47 .BR cabs (3),
  48 .BR cexp (3),
  49 .BR complex (7)