LDEXP(3) | Library Functions Manual | LDEXP(3)

# NAME

`ldexp`, `ldexpf`, `ldexpl` —
multiply floating-point number by integral power of 2

# LIBRARY

Math Library (libm, -lm)

# SYNOPSIS

`#include <math.h>`

double
`ldexp`(double x, int exp);

float
`ldexpf`(float x, int exp);

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

# DESCRIPTION

The `ldexp`() family of functions compute
x * 2^exp

for a real floating-point number x.

# RETURN VALUES

The functions return the value of x times 2 raised to the power exp. Otherwise the following may occur:

1. If x is NaN, a NaN is returned.
2. If exp is zero or x is either ± 0 or ±∞, x is returned.
3. If the call would cause an overflow, a range error occurs and either `±HUGE_VAL`, `±HUGE_VALF`, or `±HUGE_VALL` is returned, depending on the sign of x and the type of the return value.
4. If an underflow would be caused by the correct value, and the value is not representable, either 0.0 or an implementation-defined value is returned.

# SEE ALSO

frexp(3), math(3), modf(3)

# STANDARDS

The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).

March 17, 2016 | NetBSD 9.2