# `cmath` – mathematical functions for complex numbers¶

This module implements a subset of the corresponding CPython module, as described below. For more information, refer to the original CPython documentation: `cmath`.

The `cmath` module provides some basic mathematical functions for working with complex numbers.

Availability: not available on WiPy and ESP8266. Floating point support required for this module.

## Functions¶

`cmath.``cos`(z)

Return the cosine of `z`.

`cmath.``exp`(z)

Return the exponential of `z`.

`cmath.``log`(z)

Return the natural logarithm of `z`. The branch cut is along the negative real axis.

`cmath.``log10`(z)

Return the base-10 logarithm of `z`. The branch cut is along the negative real axis.

`cmath.``phase`(z)

Returns the phase of the number `z`, in the range (-pi, +pi].

`cmath.``polar`(z)

Returns, as a tuple, the polar form of `z`.

`cmath.``rect`(r, phi)

Returns the complex number with modulus `r` and phase `phi`.

`cmath.``sin`(z)

Return the sine of `z`.

`cmath.``sqrt`(z)

Return the square-root of `z`.

## Constants¶

`cmath.``e`

base of the natural logarithm

`cmath.``pi`

the ratio of a circle’s circumference to its diameter