March 21, 2006 LDEXP 3

### NAME

ldexp - multiply floating-point number by integral power of 2

### LIBRARY

Math Library (libm, -lm)

### SYNOPSIS

```double` ldexp(```double x``, int exp`)
```float` ldexpf(```float x``, int exp`)

### DESCRIPTION

The ldexp(``) function multiplies a floating-point number by an integral power of 2.

### RETURN VALUES

The ldexp(``) function returns the value of ```x` times 2 raised to the power ```exp`.

If the input x is a NaN, infinity, or 0.0, it is returned unchanged.

If the result would cause an overflow, the global variable errno is set to ```ERANGE` and infinity is returned, with the same sign as ```x`.

If the result would cause underflow to 0.0, the global variable errno is set to ```ERANGE` and the value 0.0 is returned.

### SEE ALSO

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

### STANDARDS

The ldexp(``) function conforms to ANSI X3.159-1989 (``ANSI C89'') .