ILOGB(3) Library Functions Manual ILOGB(3)

ilogb — return an unbiased exponent

#include <math.h>

int ilogb (double x)

The ilogb() function returns the exponent part of x . Formally, the return value is the integral part of log r | x | as a signed integral value, for non-zero x , where r is the radix of the machine's floating point arithmetic.

The call ilogb ( x) is equivalent to ( ) ( x).

Upon successful completion, ilogb() returns the exponent part of x.

If x is 0, then ilogb() returns -INT_MIN. If x is NaN or ±Inf, then ilogb() returns INT_MAX.

No errors are defined.

None.

None.

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logb(3) , <math.h> .

February 1997 posix.fail