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Showing content from https://cplusplus.com/reference/cmath/ldexp/ below:

function

ldexp

double ldexp (double x, int exp);

     double ldexp  (double x     , int exp);      float ldexpf (float x      , int exp);long double ldexpl (long double x, int exp);

     double ldexp (double x     , int exp);      float ldexp (float x      , int exp);long double ldexp (long double x, int exp);

     double ldexp (double x     , int exp);      float ldexp (float x      , int exp);long double ldexp (long double x, int exp);     double ldexp (T x          , int exp); // additional overloads for integral types

Generate value from significand and exponent

Returns the result of multiplying x (the significand) by 2 raised to the power of exp (the exponent).

lexpr(x,exp) = x * 2 ^exp

Header

<tgmath.h>

provides a type-generic macro version of this function.

Additional overloads

are provided in this header (

<cmath>

) for the

integral types

: These overloads effectively cast

to a

double

before calculations (defined for

being any

integral type

Parameters

x: Floating point value representing the significand.
exp: Value of the exponent.

Return Value The function returns:

x * 2 ^exp

If the magnitude of the result is too large to be represented by a value of the return type, the function returns HUGE_VAL (or HUGE_VALF or HUGE_VALL) with the proper sign, and an overflow range error occurs:

If an overflow

range error

occurs, the global variable

errno

is set to

ERANGE

Example

/* ldexp example */
#include <stdio.h>      /* printf */
#include <math.h>       /* ldexp */

int main ()
{
  double param, result;
  int n;

  param = 0.95;
  n = 4;
  result = ldexp (param , n);
  printf ("%f * 2^%d = %f\n", param, n, result);
  return 0;
}

Output:

0.950000 * 2^4 = 15.200000