### ldexp -- Multiply by a Power of Two

Format

>     #include <math.h>
>     double ldexp(double x, int exp);

Language Level: ANSI, POSIX, XPG4
ldexp calculates the value of x * (2exp).

Return Value
ldexp returns the value of x*(2exp). If an overflow results, the function returns +HUGE_VAL for a positive result or -HUGE_VAL for a negative result, and sets errno to ERANGE. If an underflow results (when the exponent is negative), the function returns 0.0, and sets errno to ERANGE.

Example
This example computes y as 1.5 times 2 to the fifth power (1.5*25):

    #include <math.h>
    #include <stdio.h>

    int main(void)
    {
       double x,y;
       int p;

       x = 1.5;
       p = 5;
       y = ldexp(x, p);
       printf("%lf times 2 to the power of %d is %lf\n", x, p, y);
       return 0;

       /***********************************************************
          The output should be:

          1.500000 times 2 to the power of 5 is 48.000000
       ***********************************************************/
    }

exp -- Calculate Exponential Function
frexp -- Separate Floating-Point Value
modf -- Separate Floating-Point Value
<math.h>