erf(3M)                        DG/UX 5.4R3.00                        erf(3M)


NAME
       erf, erfc - error function and complementary error function

SYNOPSIS
       cc [flag ...] file ...  -lm [library ...]

       #include <math.h>

       double erf (double x);

       double erfc (double x);

DESCRIPTION
       erf returns the error function of x, defined as

              2/sqrt(pi)*integral from 0 to x of e^(-t²)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 = 5, 12 places are lost).

   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |              point    safe  |
                     +---------+-----------------------------+
                     |erf      |     Y          N        N   |
                     |erfc     |     Y          N        N   |
                     +---------+-----------------------------+
SEE ALSO
       reentrant(3), exp(3M).

























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