.\" SCCSID: @(#)gamma.3m	6.3	8/30/89.\".TH gamma 3m RISC.ds nn \fINaN\fR.SH Namegamma, lgamma, signgam \- log gamma function.SH Syntax.nf.B #include <math.h>.PP.B double gamma(\fIx\fP).B double \fIx\fP;.PP.B double lgamma(\fIx\fP).B double \fIx\fP;.PP.fi.B extern int.PN signgam;.SH DescriptionThe.PN gamma.NXR "gamma subroutine".NXR "gamma function"function returns ln \||\|\(*G(\||\|\fIx\fR\||\|)\||\|.The sign of \(*G(\||\|\fIx\fR\||\|) is returned in the external integer.PN signgam .The following C program might be used to calculate \(*G:.PP.EXy = gamma(\fIx\fP);if (y > 88.0)	error();y = exp(y);if(signgam)	y = \-y;.EE.PPThe.PN lgammafunction is another name for the.PN gammafunction..SH Return ValuesThe.PN gammaand.PN lgammafunctions return \*(nn when.I xis \*(nn or when itis an integer value less than or equal to zero.  On overflow.PN gammaand.PN lgammafunctions return HUGE_VAL..SH EnvironmentWhen your program is compiled using the System V environment for nonpositive integervalues, HUGE is returned, and .I errnois set to EDOM.  A message indicating DOMAIN error is printed on the standard error output..PPIf the correct value would overflow, .PN gammareturns HUGE and sets.I errnoto ERANGE..PPThese error-handling procedures may be changed with the function.MS matherr 3m ..SH See Alsomatherr(3m)