ieee(3M)

NAME | SYNOPSIS | API RESTRICTIONS | DESCRIPTION | RETURN VALUES | ATTRIBUTES | SEE ALSO

NAME

ieee, copysign, drem, finite, logb, scalb- IEEE 754 floating point support

SYNOPSIS

$(NUCLEUS_DIR)/lib/libm.a
#include <math.h>

double copysign(double x, double y);
double drem(double x, double y);
int finite(double x);
double logb(double x);
double scalb(double x, int n);

API RESTRICTIONS

The function or functions documented here may not be used safely in all application contexts with all APIs provided in the ChorusOS 5.0 product.

See API(5FEA) for details.

DESCRIPTION

These functions are required for the IEEE 754 standard for floating-point arithmetic.

The copysign() function returns x with its sign changed to that of y .

The drem() function returns the remainder r as follows:

r : = x - n*y

Where, n is the integer closest to the exact value of x/y . If | n - x/y | = 1/2, then n is even. Consequently, the remainder is computed exactly and | r | <= | y | / 2.

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Note -

drem x 0() is exceptional.

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The finite() function returns true (1) if the argument x is neither infinity nor NaN ( N ot a N umber) value. Otherwise, it returns false (0).

The logb() function computes the exponent of x , which is the integral part of log2 | x | , as a signed floating point value for nonzero x .

The scalb() function returns x * (2** n ) computed, for integer n , without first computing 2** n .

RETURN VALUES

The IEEE 754 standard defines drem x 0() and drem infinity y() as invalid operations that produce a NaN .

IEEE 754 defines logb +- infinity() = + infinity , and logb 0() = -HUGE_VAL , and requires the latter to signal Division-by-Zero. On successful completion, logb() returns the exponent of x .

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving

SEE ALSO

floor(3M) , Intro(3M) , infnan(3M)

ChorusOS 5.0  Last Revised December 2001

NAME | SYNOPSIS | API RESTRICTIONS | DESCRIPTION | RETURN VALUES | ATTRIBUTES | SEE ALSO