/C

# exp, expf, expl

Defined in header `<math.h>`
`float       expf( float arg );`
(1) (since C99)
`double      exp( double arg );`
(2)
`long double expl( long double arg );`
(3) (since C99)
Defined in header `<tgmath.h>`
`#define exp( arg )`
(4) (since C99)
1-3) Computes the e (Euler's number, `2.7182818`) raised to the given power `arg`.
4) Type-generic macro: If `arg` has type `long double`, `expl` is called. Otherwise, if `arg` has integer type or the type `double`, `exp` is called. Otherwise, `expf` is called. If `arg` is complex or imaginary, then the macro invokes the corresponding complex function (`cexpf`, `cexp`, `cexpl`).

### Parameters

 arg - floating point value

### Return value

If no errors occur, the base-e exponential of `arg` (earg
) is returned.

If a range error due to overflow occurs, `+HUGE_VAL`, `+HUGE_VALF`, or `+HUGE_VALL` is returned.

If a range error occurs due to underflow, the correct result (after rounding) is returned.

### Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

• If the argument is ±0, 1 is returned
• If the argument is -∞, +0 is returned
• If the argument is +∞, +∞ is returned
• If the argument is NaN, NaN is returned

For IEEE-compatible type `double`, overflow is guaranteed if 709.8 < arg, and underflow is guaranteed if arg < -708.4.

### Example

```#include <stdio.h>
#include <math.h>
#include <float.h>
#include <errno.h>
#include <fenv.h>
#pragma STDC FENV_ACCESS ON
int main(void)
{
printf("exp(1) = %f\n", exp(1));
printf("FV of \$100, continuously compounded at 3%% for 1 year = %f\n",
100*exp(0.03));
// special values
printf("exp(-0) = %f\n", exp(-0.0));
printf("exp(-Inf) = %f\n", exp(-INFINITY));
//error handling
errno = 0; feclearexcept(FE_ALL_EXCEPT);
printf("exp(710) = %f\n", exp(710));
if(errno == ERANGE) perror("    errno == ERANGE");
if(fetestexcept(FE_OVERFLOW)) puts("    FE_OVERFLOW raised");
}```

Possible output:

```exp(1) = 2.718282
FV of \$100, continuously compounded at 3% for 1 year = 103.045453
exp(-0) = 1.000000
exp(-Inf) = 0.000000
exp(710) = inf
errno == ERANGE: Numerical result out of range
FE_OVERFLOW raised```
• C11 standard (ISO/IEC 9899:2011):
• 7.12.6.1 The exp functions (p: 242)
• 7.25 Type-generic math <tgmath.h> (p: 373-375)
• F.10.3.1 The exp functions (p: 520)
• C99 standard (ISO/IEC 9899:1999):
• 7.12.6.1 The exp functions (p: 223)
• 7.22 Type-generic math <tgmath.h> (p: 335-337)
• F.9.3.1 The exp functions (p: 458)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.5.4.1 The exp function

 exp2exp2fexp2l (C99)(C99)(C99) computes 2 raised to the given power (2x) (function) expm1expm1fexpm1l (C99)(C99)(C99) computes e raised to the given power, minus one (ex-1) (function) loglogflogl (C99)(C99) computes natural (base-e) logarithm (ln(x)) (function) cexpcexpfcexpl (C99)(C99)(C99) computes the complex base-e exponential (function) C++ documentation for `exp`