Legacy Document

exp

You can use the exp function to raise e to some power.

double_t exp (double_t x);

x

Any floating-point number.

DESCRIPTION

The exp function performs the exponential function on its argument.

$exp(x)\; =\; ex$

The log function performs the inverse operation $(lnex)$ .

EXCEPTIONS

When x is finite and nonzero, the result of $exp(x)$ might raise the following exceptions:

• inexact (for all finite, nonzero values of x)
• overflow (if the result is outside the range of the data type)
• underflow (if the result is inexact and must be represented as a denormalized number or 0)

SPECIAL CASES

Table 10-7 shows the results when the argument to the exp function is a zero, a NaN, or an Infinity.

Special cases for the exp function

Operation	Result	Exceptions raised
$exp(+0)$	+1	None
$exp(-0)$	+1	None
$exp(NaN)$	NaN	None[28]
$exp(+$ )	+	None
$exp(-$ )	+0	None

EXAMPLES

z = exp(0.0);  /* z = e0 = 1. */
z = exp(1.0);  /* z = e1  2.71828128 . . . The inexact exception is 
                  raised. */

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[28] If the NaN is a signaling NaN, the invalid exception is raised.