.\" SCCSID: @(#)erf.3m	8.2	3/28/91'\" e.TH erf 3m VAX.SH Nameerf, erfc \- error function and complementary error function.SH Syntax.B #include <math.h>.PP.B double erf (x).br.B double x;.PP.B double erfc (x).br.B double x;.SH Description.if t .ig.PPNOTE: Your terminal may not be able to accurately display the special math symbols in this reference page. See the .I ULTRIX Programmer's Manual, Unsupportedfor a complete description of the math symbols. ...NXR "erf subroutine".NXR "erfc subroutine" .NXR "error function".PPThe.PN erffunction returns the error function of.IR x ,defined as.EQ.nr 99 \n(.s.nr 98 \n(.f.ps 10.ft 1.ds 11 "\f12\fP.ds 12 "\(*p.nr 12 \w'\s10\*(12'.ds 12 \v'0u'\e\L'-40u'\l'\n(12u'\v'40u'\h'-\n(12u'\*(12.nr 11 \w'\s10\*(11'.nr 12 \w'\s10\*(12'.nr 13 \n(11.if \n(12>\n(13 .nr 13 \n(12.ds 11 \v'40u'\h'\n(13u-\n(12u/2u'\*(12\\h'-\n(12u-\n(11u/2u'\v'-60u'\*(11\\h'-\n(13u-\n(11u-2u/2u'\v'0u'\l'\n(13u'\v'20u'.ds 12 \(is.ds 13 "\f10\fP.ds 14 "x.nr 12 \w'\s10\*(12'.nr 15 \n(12.nr 13 \w'\s7\*(13'.if \n(13>\n(15 .nr 15 \n(13.nr 14 \w'\s7\*(14'.if \n(14>\n(15 .nr 15 \n(14.ds 15 \v'40u'\h'\n(15u-\n(13u/2u'\s7\*(13\s10\h'-\n(15u-\n(13u/2u'\v'-40u'\\h'\n(15u-\n(12u/2u'\*(12\h'\n(15u-\n(12u+2u/2u'\\v'-40u'\h'-\n(15u-\n(14u/2u'\s7\*(14\s10\h'\n(15u-\n(14u/2u'\v'40u'\.as 11 "\*(15.ds 12 "e.ds 13 "\(mi.ds 14 "t.ds 15 "\f12\fP.as 14 \v'-20u'\*(15\v'20u'.as 13 "\|\*(14.as 12 \v'-20u'\*(13\v'20u'.as 11 "\*(12.ds 12 "dt.as 11 "\|\*(12.ds 12 "..as 11 "\*(12.ds 11 \x'0'\x'0-20u'\f1\s10\*(11\s\n(99\f\n(98\x'20u'.nr 11 \w'\*(11'.nr MK 0.if 120>\n(.v .ne 120u.rn 11 10\*(10.ps \n(99.ft \n(98.EN.PPThe.PN erfcfunction,which returns 1.0 \-.IR erf(x) ,is provided because of theextreme loss of relative accuracy if.I erf(x)is called for large.I xand the result subtractedfrom 1.0 (e.g. for.I x= 5, 12 places are lost)..SH See Alsoexp(3m).br.I ULTRIX Programmer's Manual, Unsupported