ISINF(3) MachTen Programmer’s Manual ISINF(3)

NAME
isinf, isnan - test for infinity or not-a-number

SYNOPSIS
int
isinf(double)

int
isnan(double)

DESCRIPTION
The isninf() function returns 1 if the number is ‘‘infinity’’, otherwise
0.

The isnan() function returns 1 if the number is ‘‘not-a-number’’, other-
wise 0.

SEE ALSO
math(3)

IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI.

BUGS
Neither the VAX nor the Tahoe floating point have distinguished values
for either infinity or not-a-number. These routines always return 0 on
those architectures.

4.4BSD January 29, 1994 1