erf

Error function.

SYNOPSIS:

double x, y, erf();
y = erf(x);

DESCRIPTION:

The integral is
x
-
2 | | 2
erf(x) = -------- | exp(- t) dt.
sqrt(pi) | |
-
0

The magnitude of x is limited to 9.231948545 for DEC arithmetic; 1 or -1 is returned outside this range.
For 0 <= |x| < 1, erf(x) = x * P4(x**2)/Q5(x**2); otherwise erf(x) = 1 - erfc(x).

ACCURACY:
Relative error:
arithmetic domain # trials peak rms
DEC 0,1 14000 4.7e-17 1.5e-17
IEEE 0,1 30000 3.7e-16 1.0e-16