p?lasnbt

Computes the position of the sign bit of a floating-point number. (C interface function).

Syntax

void pslasnbt(int *ieflag);

void pdlasnbt(int *ieflag);

Description

The p?lasnbt routine finds the position of the signbit of a single/double precision floating point number. This routine assumes IEEE arithmetic, and hence, tests only the 32-nd bit (for single precision) or 32-nd and 64-th bits (for double precision) as a possibility for the signbit. sizeof(int) is assumed equal to 4 bytes.

If a compile time flag (NO_IEEE) indicates that the machine does not have IEEE arithmetic, ieflag = 0 is returned.

Output Parameters

ieflag

INTEGER.

This flag indicates the position of the signbit of any single/double precision floating point number.

ieflag = 0, if the compile time flag NO_IEEE indicates that the machine does not have IEEE arithmetic, or if sizeof(int) is different from 4 bytes.

ieflag = 1 indicates that the signbit is the 32-nd bit for a single precision routine.

In the case of a double precision routine:

ieflag = 1 indicates that the signbit is the 32-nd bit (Big Endian).

ieflag = 2 indicates that the signbit is the 64-th bit (Little Endian).

See Also

For more complete information about compiler optimizations, see our Optimization Notice.