Guardian Native C Library Calls Reference Manual (G06.29+, H06.08+, J06.03+)

Guardian Native C Library Calls (g - i) isnan(3)
compiler directive.
NOTES
isnan() Macro
The isnan( ) macro is implemented only for the IEEE_float floating-point option. Applications
using this macro cannot be compiled if the specified floating-point option is Tandem_float.
isnan() Function
Tandem floating-point format does not support NaN values; the isnan( ) function returns a value
of 0 (zero) for Tandem floating-point data.
If you call the isnan( ) function with an IEEE floating-point value for the x parameter that is a
signaling NaN, an exception occurs. To test for a signaling NaN without causing an exception,
call the fp_class() function.
RETURN VALUES
isnan() Macro
The isnan( ) macro returns a nonzero value if and only if its argument has a NaN value.
isnan() Function
Tandem floating-point format does not support NaN values. Thus, the isnan( ) function returns a
value of 0 (zero) for Tandem floating-point data.
When used for IEEE floating-point data, the isnan() function returns TRUE if the value
specified for the x parameter is not a number. Otherwise, the value FALSE is returned.
ERRORS
No errors are defined.
RELATED INFORMATION
isnan() Macro
Functions: fpclassify(3), isfinite(3), isinf(3), isnormal(3), signbit(3).
Files: math(4).
isnan() Function
Functions: fp_class(3).
STANDARDS CONFORMANCE
isnan() Macro
The isnan( ) macro conforms to the ISO/IEC 9899:1999 standard.
The isnan( ) macro conforms to the IEEE Std 1003.1, 2004 Edition.
isnan() Function
The isnan( ) function conforms to the XPG4 Version 2 specification when used for IEEE
floating-point format data.
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