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exp, expl

Header File

math.h

Category

Math Routines

Prototype

double exp(double x);

long double expl(long double x);

Description

Calculates the exponential e to the x.

expl is the long double version; it takes a long double argument and returns a long double result.

Return Value

exp returns e to the x.

Sometimes the arguments passed to these functions produce results that overflow or are incalculable. When the correct value overflows, exp returns the value HUGE_VAL and expl returns _LHUGE_VAL. Results of excessively large magnitude cause the global variable errno to be set to

ERANGE | Result out of range

On underflow, these functions return 0.0, and the global variable errno is not changed. Error handling for these functions can be modified through the functions _matherr and _matherrl.

Example

Copy Code

    #include <stdio.h>
    #include <math.h>
    int main(void)
    {
       double result;
       double x = 4.0;
       result = exp(x);
       printf("'e' raised to the power \
              of %lf (e ^ %lf) = %lf\n",
              x, x, result);
       return 0;
    }

Portability

| POSIX | Win32 | ANSI C | ANSI C++
exp | + | + | + | +
expl |  | + | + | +

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