ldexp, ldexpl

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Header File

math.h

Category

Math Routines

Prototype

double ldexp(double x, int exp);

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

Description

Calculates x * 2^exp.

lexpl is the long double version; it takes a long double argument for x and returns a long double result.

Return Value

On success, ldexp (or ldexpl) returns the value it calculated, x * 2^exp. Error handling for these routines can be modified through the functions _matherr and _matherrl.

Example

#include <stdio.h>
#include <math.h>
int main(void)
{
    double value;
    double x = 2;
    /* ldexp raises 2 by a power of 3
       then multiplies the result by 2   */
    value = ldexp(x,3);
    printf("The ldexp value is: %lf\n", value);
    return 0;
}
 

Portability

	POSIX	Win32	ANSI C	ANSI C++
ldexp	+	+	+	+
ldexpl		+	+	+