exp, expf, expl

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
Functions
Basic operations
(C99)
(C99)
(C99)
(C99)(C99)(C99)(C23)
Maximum/minimum operations
(C99)
(C23)    
Exponential functions
exp
(C23)
(C99)
(C99)
(C23)
(C23)
(C99)
(C99)(C23)
(C23)
(C23)
Power functions
(C99)
(C23)
(C23)
(C99)
(C23)
(C23)
Trigonometric and hyperbolic functions
(C23)
(C23)
(C23)
(C23)
(C99)
(C99)
(C99)
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99)(C99)(C99)
(C99)
(C99)(C99)(C99)
(C23)(C23)(C23)(C23)
Floating-point manipulation functions
(C99)(C99)
(C99)(C23)
(C99)
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
(C99)
(C99)
(C99)
(C23)
Types
(C99)(C99)    

(C99)(C99)    

Macro constants
Special floating-point values
(C99)(C23)
Arguments and return values
(C99)(C99)(C99)(C99)(C99)    
Error handling
 
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.
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 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.

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

Notes

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

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

References

  • C23 standard (ISO/IEC 9899:2023):
  • 7.12.6.1 The exp functions (p: TBD)
  • 7.25 Type-generic math <tgmath.h> (p: TBD)
  • F.10.3.1 The exp functions (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.12.6.1 The exp functions (p: 175)
  • 7.25 Type-generic math <tgmath.h> (p: 272-273)
  • F.10.3.1 The exp functions (p: 379)
  • 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

See also

(C99)(C99)(C99)
computes 2 raised to the given power (2x)
(function)
(C99)(C99)(C99)
computes e raised to the given power, minus one (ex-1)
(function)
(C99)(C99)
computes natural (base-e) logarithm (ln(x))
(function)
(C99)(C99)(C99)
computes the complex base-e exponential
(function)