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home | helpISNAN(3) BSD Library Functions Manual ISNAN(3) NAME isnan -- test for not-a-number LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <math.h> int isnan(real-floating x); DESCRIPTION The isnan() macro determines whether its argument x is not-a-number ("NaN"). 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. IEEE 754 It is determined whether the value of x is a NaN. VAX NaNs are not supported. RETURN VALUES The isnan() macro returns a non-zero value if the value of x is a NaN. Otherwise 0 is returned. SEE ALSO fpclassify(3), isfinite(3), isinf(3), isinff(3), isnanf(3), isnormal(3), math(3), signbit(3) IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI. STANDARDS The isnan() macro conforms to ISO/IEC 9899:1999 ("ISO C99"). BSD March 5, 2004 BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | STANDARDS