Content-type: text/html Man page of ldexp

ldexp

Section: Mathematical Library Functions (3M)
Updated: 12 Jul 2006
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NAME

ldexp, ldexpf, ldexpl - load exponent of a floating point number  

SYNOPSIS

c99 [ flag... ] file... -lm [ library... ]
#include <math.h>

double ldexp(double x, int exp);

float ldexpf(float x, int exp);

long double ldexpl(long double x, int exp);  

DESCRIPTION

These functions computes the quantity x* 2 **exp .  

RETURN VALUES

Upon successful completion, these functions return x multiplied by 2 raised to the power exp.

If these functions would cause overflow, a range error occurs and ldexp(), ldexpf(), and ldexpl() return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (according to the sign of x), respectively.

If x is NaN, a NaN is returned.

If x is ±0 or ±Inf, x is returned.

If exp is 0, x is returned.  

ERRORS

These functions will fail if:

Range Error The result overflows.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.

The ldexp() function sets errno to ERANGE if the result overflows.

 

USAGE

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

An application can also set errno to 0 before calling ldexp(). On return, if errno is non-zero, an error has occurred. The ldexpf() and ldexpl() functions do not set errno.  

ATTRIBUTES

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

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard
MT-LevelMT-Safe

 

SEE ALSO

frexp(3M), isnan(3M), modf(3M), attributes(5), standards(5)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
ERRORS
USAGE
ATTRIBUTES
SEE ALSO

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Time: 02:39:32 GMT, October 02, 2010