NAME
isinf —
test for infinity
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <math.h>
int
isinf(
real-floating
x);
DESCRIPTION
The
isinf() macro determines whether its argument
x is an infinity (positive or negative). An argument
represented in a format wider than its semantic type is converted to its
semantic type first. The determination is then based on the type of the
argument.
RETURN VALUES
The
isinf() macro returns a non-zero value if the value of
x is an infinity. Otherwise 0 is returned.
SEE ALSO
fpclassify(3),
isfinite(3),
isinff(3),
isnan(3),
isnanf(3),
isnormal(3),
math(3),
signbit(3)
IEEE Standard for Binary Floating-Point
Arithmetic, Std 754-1985,
ANSI.
STANDARDS
The
isinf() macro conforms to
ISO/IEC
9899:1999 (“ISO C99”).
CAVEATS
On VAX the
isinf() function always returns 0, as the
architecture doesn't have a representation for infinity.