.TH erf 3m RISC.ds nn \fINaN\fR.SH Nameerf, erfc \- error functions.SH Syntax.nf.B #include <math.h>.PP.B double erf(\fIx\fP).B double \fIx\fP;.PP.B double erfc(\fIx\fP).B double \fIx\fP;.fi.SH Description.NXR "erf function".NXR "erfc function"The .PN erf function returns the error function of.I xdefined as follows:.EXerf(x) = 2/sqrt(pi)\(**\|integral from 0 to x of exp(\-t\(**t) dt. \}.EE.PPThe .PN erfcfunction returns 1.0\-erf\|(\fIx\fP)..PPThe entry for the.PN erfc function is provided because of the extreme lossof relative accuracy if erf\|(\fIx\fP) is called for large.I xand the result subtracted from 1.For example if.I x= 10, 12 places are lost..SH Return ValuesThe.PN erfand.PN erfcfunctions return \*(nn when.I xis \*(nn..SH See Alsomath(3m)