The exp () function and ldexp () function of C language and the Frexp () function _c language

C language exp () function: The second power function of E (the x-th square value at the end of E)
header file:

#include <math.h>

EXP () is used to calculate the X-square value, the ex value, at the base of E, and then return the result. Its prototype is:

  Double exp (double x);

return value returns the X-square calculation of E.

Note that when compiling with GCC, please join-LM.

"Instance" calculates the value of the 10-second side of E.

#include <math.h>
Main () {
  double answer;
  Answer = exp (ten);
  printf ("e^10 =%f\n", answer);
}

Run Result:

E^10 = 22026.465795

C language Ldexp () function: Returns the value of the exp second square on x multiplied by 2
header file:

#include <math.h>

Ldexp () is used to find the value of the exp second side of a number multiplied by 2, and the prototype is:

Double Ldexp (double x, int exp);

"Parameter" x is the mantissa, and exp is the power number.

Set the return value to RET, then ret = x * 2exp

Return value returns the RET.

Note that when compiling with GCC, please join-LM.

The "example" computes the value of 3* (2^2).

#include <math.h>
Main () {
  int exp;
  Double x, answer;
  Answer = LDEXP (3, 2);
  printf ("3*2^ (2) =%f\n", answer);
}

Operation Result:

3*2^ (2) = 12.000000

C language Frexp () function: To decompose a floating-point number into mantissa and exponent
header file:

#include <math.h>

Frexp () is used to decompose a number into mantissa and exponent, and its prototype is:

  Double Frexp (double x, int *exp);

"Parameter" x is a floating-point number to be decomposed, and exp is a pointer to the storage index.

Set the return value to RET, then x = ret * 2exp, where exp is an integer, and the absolute value of the RET is between 0.5 (inclusive) and 1 (not included).

If x = 0, then ret = exp = 0

Return value returns the MANTISSA ret.

Note that when compiling with GCC, please join-LM.

Take a look at the following code:

#include <stdio.h>   /* printf
/#include <math.h>    /* frexp
/int main ()
{
  double param, result;
  int n;
  param = 8.0;
  result = Frexp (param, &n);
  printf ("%f =%f * 2^%d\n", param, result, n);
  return 0;
}

Output results:

8.000000 = 0.500000 * 2^4

To change the value of line 7th param to 242.354, the output is:

242.354000 = 0.946695 * 2^8