Contents

Interface Description Special Values See Also Standards Page Comments

Interface

#include <math.h>

	double	exp (double x)
	long	expl (long double x)
	float	expf (float x)
	double	exp2 (double x)
	long	exp2l (long double x)
	float	exp2f (float x)
	double	expm1 (double x)
	long	expm1l (long double x)
	float	expm1f (float x)

Description

The exp function computes , the base-e exponential of x.

The exp2 function computes , the base-2 exponential of x.

The expm1 function computes the base-e exponential of x, minus 1, accurately even for very small values of x.

Example 1:

#include <stdio.h>
#include <math.h>
 
int main(void)
{
  double result, x = 4.34;
  result = exp(x);
  printf("'e' raised to the power of %.2lf (e^%.2lf) = %.2lf\n", x, x, result);
  return 0;
}

Output:

'e' raised to the power of 4.34 (e^4.34) = 76.71

Special Values

exp ( ±0 ) and exp2 ( ±0 ) return 1.
exp ( -∞ ) and exp2 ( -∞ ) return +0.
exp ( +∞ ) and exp2 ( +∞ ) return +∞.
expm1 ( ±0 ) returns ±0.
expm1 ( -∞ ) returns -1.
expm1 ( +∞ ) returns +∞.

For all these functions, a range error occurs if the magnitude of x is too large.

See Also

log, pow

Standards

The exp, exp2 and expm1 functions conform to ISO/IEC 9899:1999(E).

Page Comments

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