### cis (Function)

##### Syntax:

— Function:

**cis**` radians `→` number`
##### Arguments and Values:

`radians`—a *real*.

`number`—a *complex*.

##### Description:

`cis`

returns the value of *e*^i· *radians*,
which is a *complex* in which the
real part is equal to the cosine of `radians`, and the
imaginary part is equal to the sine of `radians`.

##### Examples:

(cis 0) → #C(1.0 0.0)

##### See Also:

Section 12.1.3.3 (Rule of Float Substitutability)