man3/erf.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  28 .\" Modified 2002-07-27 by Walter Harms
  29 .\"     (walter.harms@informatik.uni-oldenburg.de)
  30 .\"
  31 .TH ERF 3  2002-07-27 "BSD" "Linux Programmer's Manual"
  32 .SH NAME
  33 erf, erff, erfl, erfc, erfcf, erfcl \- error function and complementary error function
  34 .SH SYNOPSIS
  35 .nf
  36 .B #include <math.h>
  37 .sp
  38 .BI "double erf(double " x );
  39 .br
  40 .BI "float erff(float " x );
  41 .br
  42 .BI "long double erfl(long double " x );
  43 .sp
  44 .BI "double erfc(double " x );
  45 .br
  46 .BI "float erfcf(float " x );
  47 .br
  48 .BI "long double erfcl(long double " x );
  49 .sp
  50 .fi
  51 Link with \-lm.
  52 .SH DESCRIPTION
  53 The \fBerf\fP() function returns the error function of \fIx\fP; defined
  54 as
  55 .TP
  56 erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(\-t*t) dt
  57 .PP
  58 The \fBerfc\fP() function returns the complementary error function of
  59 \fIx\fP, that is 1.0 \- erf(x).
  60 .SH "CONFORMING TO"
  61 SVr4, 4.3BSD, C99.
  62 The
  63 .I float
  64 and
  65 .I "long double"
  66 variants are requirements of C99.
  67 .SH "SEE ALSO"
  68 .BR cerf (3),
  69 .BR exp (3)