# Precision of new Math APIs

## Math.log1p

The built-in function Math.log1p(x)
calculates the value of the expression `Math.log(1 + x)`

. At first glance it may seem
strange to include such a simple helper, but its purpose is not convenience but to preserve
precision when x is very small. Take a look at the following chart:

## Math.expm1

The built-in function Math.expm1(x)
calculates the value of the expression `Math.pow(Math.E, x) - 1`

.

Again note that doing this calculation by hand results in significant loss of precision when x is very small.