EXPM1

Description

The expm1 function is used to calculate the value of exp(expr)-1, where expr is a double type parameter. This function can avoid numerical overflow or precision issues that may occur when directly calculating exp(x), and is particularly suitable for calculating smaller exponential values.

Functionality

This function calculates the value of e raised to the power of expr minus 1, where e is the base of the natural logarithm (approximately equal to 2.71828). This calculation method has advantages in numerical stability, especially when dealing with exponential values close to zero.

Parameters

• expr (double type): The value for which the exponential complement needs to be calculated.

Return Value

Returns a double type value representing the result of exp(expr)-1.

Usage Example

Here are some examples of using the expm1 function:

1. Calculate the value of exp(1)-1:

   SELECT expm1(1);
   

Result:

1.718281828459045

2. Calculate the value of exp(0.5)-1:

   SELECT expm1(0.5);
   

Result:

0.6487212707001282

3. Calculate the value of exp(-1)-1:

   SELECT expm1(-1);
   

Result:

-0.6321205588285577

4. Calculate the values of a series of exponential complements:

   SELECT expm1(-0.1), expm1(0), expm1(0.1), expm1(1);
   

Result:

-0.09516258196404043, 0, 0.10517091807564763, 1.718281828459045