exp function

Synopsis

$exp(<number>)

Technical

Returns the value of e raised to number, where e is the base of natural logarithms. Every finite real number is in its mathematical domain. The inverse operation for positive values is $log().

The normal rules about number arguments apply. The first argument word is converted with atof(), accepting decimal fractions and scientific notation; additional words are ignored. Missing input returns the empty string. Nonnumeric input converts to zero, and a numeric prefix can be accepted even when followed by nonnumeric text.

Returns and restrictions

The calculation uses the C library's exp() and a C double. Successful results are formatted with %.50g, rather than being limited to six decimal places. The floating_point_math and floating_point_precision settings do not change this calculation or formatting. Extra displayed digits do not imply 50 digits of accuracy.

Large positive finite inputs can overflow; sufficiently negative finite inputs can underflow to a very small value or zero. If the library reports a range error through errno, EPIC returns RANGE. If it does not, EPIC formats the library's returned value instead. Positive infinity ordinarily produces positive infinity, negative infinity produces zero, and NaN produces NaN.

The shared wrapper also returns DOM for a reported domain error and the empty string for another reported error. It checks errno, rather than floating-point exception flags, and clears errno after argument conversion and before calculating the exponential.

Examples

The approximate examples describe numeric values; returned strings may contain more digits.

Source

source/functions.c registers exp and implements it through the shared math-function and error-return macros. include/functions.h defines argument conversion and formatting. C floating-point special-value guidance discusses infinite inputs, and POSIX mathematical error rules describe range-error reporting.