# `cmath` – 复数的数学函数¶

This module is always available. It provides access to mathematical functions for complex numbers.

`cmath.``acos`(z, /)

Return the arc cosine of z.

`cmath.``acosh`(z, /)

Return the inverse hyperbolic cosine of z.

`cmath.``asin`(z, /)

Return the arc sine of z.

`cmath.``asinh`(z, /)

Return the inverse hyperbolic sine of z.

`cmath.``atan`(z, /)

Return the arc tangent of z.

`cmath.``atanh`(z, /)

Return the inverse hyperbolic tangent of z.

`cmath.``cos`(z, /)

Return the cosine of z.

`cmath.``cosh`(z, /)

Return the hyperbolic cosine of z.

`cmath.``exp`(z, /)

Return the exponential value e**z.

`cmath.``isclose`(a, b, *, rel_tol=1e-09, abs_tol=0.0)

Determine whether two complex numbers are close in value.

rel_tol

maximum difference for being considered “close”, relative to the magnitude of the input values

abs_tol

maximum difference for being considered “close”, regardless of the magnitude of the input values

Return True if a is close in value to b, and False otherwise.

For the values to be considered close, the difference between them must be smaller than at least one of the tolerances.

-inf, inf and NaN behave similarly to the IEEE 754 Standard. That is, NaN is not close to anything, even itself. inf and -inf are only close to themselves.

`cmath.``isfinite`(z, /)

Return True if both the real and imaginary parts of z are finite, else False.

`cmath.``isinf`(z, /)

Checks if the real or imaginary part of z is infinite.

`cmath.``isnan`(z, /)

Checks if the real or imaginary part of z not a number (NaN).

`cmath.``log`(x, y_obj=None, /)

The logarithm of z to the given base.

If the base not specified, returns the natural logarithm (base e) of z.

`cmath.``log10`(z, /)

Return the base-10 logarithm of z.

`cmath.``phase`(z, /)

Return argument, also known as the phase angle, of a complex.

`cmath.``polar`(z, /)

Convert a complex from rectangular coordinates to polar coordinates.

r is the distance from 0 and phi the phase angle.

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

Convert from polar coordinates to rectangular coordinates.

`cmath.``sin`(z, /)

Return the sine of z.

`cmath.``sinh`(z, /)

Return the hyperbolic sine of z.

`cmath.``sqrt`(z, /)

Return the square root of z.

`cmath.``tan`(z, /)

Return the tangent of z.

`cmath.``tanh`(z, /)

Return the hyperbolic tangent of z.