erf(3F)

NAME
     erf, erfc, derf, derfc, qerf, qerfc - error function and complementary
     error function

SYNOPSIS
     real*4 r1, r2, erf
     real*8 dp1, dp2, derf
     real*16 cd1, cd2, qerf

     r2 = erf(r1)
     dp2 = derf(dp1)
     cd2 = qerf(cd1)

     real*4 r1, r2, erfc
     real*8 dp1, dp2, derfc
     real*16 cd1, cd2, qerfc

     r2 = erfc(r1)
     dp2 = derfc(dp1)
     cd2 = qerfc(cd1)

DESCRIPTION
     erf returns the error function of x, defined as

             (2/sqrt(pi)) integral{0 to x} of (e ** -t **2)  dt.






     erfc, which returns 1.0 - erf(x), is provided because of the extreme loss
     of relative accuracy if erf(x) is called for large x and the result
     subtracted from 1.0 (e.g., for x = 10, 12 places are lost).

     The standard math library libm.a, libmx.a, and libm43.a each contain
     versions of these functions.

DIAGNOSTICS
     In the diagnostics below, functions in the standard math library libm.a,
     are referred to as -lm versions, those in math library libmx.a are
     referred to as -lmx versions, and those in the the BSD math library
     libm43.a are referred to as -lm43 versions.  The -lm and -lmx versions
     always return the default Quiet NaN and set errno to EDOM when a NaN is
     used as an argument.  A NaN argument usually causes the -lm43 versions to
     return the same argument.  The -lm43 versions never set errno.

     See matherr(3M) for a description of error handling for -lmx functions.
SEE ALSO
     exp(3M), matherr(3M)