NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ATTRIBUTES | SEE ALSO
#include <math.h>double copysign(double x, double y);
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 := x - n*y where n is the integer closest to the exact value of x/y . If | n - x/y | = 1/2, n is even. Consequently, the remainder is computed exactly and | r | <= | y | / 2. Note that drem (x, 0) is exceptional.
The finite () function returns true (1) if the argument x is neither inifinity nor NaN 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 non-zero x.
The scalb () function returns x * (2**n) computed, for integer n, without first computing 2**n.
The IEEE 754 standard defines drem(x, 0) and drem( infinity , y) to be 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. Upon successful completion, logb() returns the exponent of x.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
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Interface Stability | Evolving |
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ATTRIBUTES | SEE ALSO