Returns its first argument multiplied by 2 raised to the power of
    its second argument; that is, x(2n).

    Format

      #include  <math.h>

      double ldexp  (double x, int n);

      float ldexp  (float x, int n); (Integrity servers, Alpha)

      long double ldexp  (long double x, int n);
                         (Integrity servers, Alpha)