exp, expf, expl - cppreference.com (original) (raw)

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 e (Euler's number, 2.7182818...) raised to the given power arg.

  1. 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).

Contents

[edit] Parameters

arg - floating-point value

[edit] Return value

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

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

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

[edit] Error handling

Errors are reported as specified in math_errhandling.

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

[edit] Notes

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

[edit] Example

#include <errno.h> #include <fenv.h> #include <float.h> #include <math.h> #include <stdio.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

[edit] References

[edit] See also