Functions

1. Single-valued function http://mathworld.wolfram.com/Single-ValuedFunction.html
2. Multi-valued function http://mathworld.wolfram.com/MultivaluedFunction.html

Example:
1. Single-valued function
Integer power function:
f(x) = x^2, etc.
Other: trigonometric, hyperbolic, exponential and integer power function. 


2. Multi-valued function
f(x) = root(x), etc.

To draw single-valued function:
To draw multi-valued function: