Section (3) erfc
erfc, erfcf, erfcl — complementary error function
||long double x
On success, these functions return the complementary error
value in the range [0,2].
x is a NaN, a
NaN is returned.
x is +0 or
−0, 1 is returned.
x is positive
infinity, +0 is returned.
x is negative
infinity, +2 is returned.
If the function result underflows and produces an unrepresentable value, the return value is 0.0.
If the function result underflows but produces a representable (i.e., subnormal) value, that value is returned, and a range error occurs.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
Range error: result underflow(
result is subnormal)
An underflow floating-point exception (
FE_UNDERFLOW) is raised.
These functions do not set
For an explanation of the terms used in this section, see attributes(7).
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
erfcl() functions are provided to avoid the
loss accuracy that would occur for the calculation 1-erf(x)
for large values of
(for which the value of erf(x) approaches 1).
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