exp
exponential functions
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NAME
exp, exp2, expm1
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 = 4.0;
result = exp(x);
printf("'e' raised to the power of %lf (e^%lf)=%lf\n", x, x, result);
return 0;
}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.
STANDARDS
The exp , exp2 , and expm1 functions conform to ISO/IEC 9899:1999(E).