Guardian Native C Library Calls Reference Manual (G06.28+, H06.04+)

Guardian Native C Library Calls (f) frexp(3)
NAME
frexp - Breaks a floating-point number into a fraction and a power of 2
LIBRARY
G-series native Guardian processes: $SYSTEM.SYSnn.ZCRESRL
G-series native OSS processes: /G/system/sysnn/zcresrl
H-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCREDLL
H-series OSS processes: /G/system/zdllnnn/zcredll
SYNOPSIS
#include <math.h>
double frexp(
double value,
int *exp
);
PARAMETERS
value Specifies the double value to be broken into a fraction and a power of 2.
exp Is an integer pointer specifying where to store the exponent of 2.
DESCRIPTION
Every nonzero number can be written uniquely as x times 2 raised to the power n, where the
mantissa (fraction), x, is in the range 0.5 ≤ |x| < 1.0, and the exponent, n, is an integer.
The frexp() function breaks the floating-point number value into a normalized fraction and an
integral power of 2. It stores the integral power of 2 in the int object pointed to by the exp
parameter and returns the normalized fraction part.
NOTES
This function supports both IEEE Std 754-1985 floating-point and Tandem floating-point values
in the native environment. IEEE values can include NaN and infinity, and the sign of 0.0 (zero)
can be either positive or negative. Refer to the fp_class(3) reference page for a description of
IEEE value classes.
Guardian functions are available to convert between floating-point formats. Refer to the Guar-
dian Programmer’s Guide for a discussion of floating-point conversions.
RETURN VALUES
Upon successful completion, the frexp() function returns the value x such that x is a double with
magnitude in the interval 1/2 to 1, or 0.0 (zero), and value equals x times 2 raised to the power of
*exp.
If the value of value is 0.0 (zero), both the returned function value and the returned value of *exp
are zero.
For IEEE floating-point values, if the value of value is NaN, then the returned function value is
NaN. If the value of value is positive or negative infinity, then the returned function value is the
value of value and errno is set to [EDOM].
ERRORS
If any of the following conditions occurs, the frexp() function sets errno to the corresponding
value:
[EDOM] The value parameter is infinity.
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