# 5.3.6 cmath

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