Complex analysis is a branch of mathematics that studies functions of complex numbers.

A complex number is a combination of a real number and an imaginary number.

He works in the marketing division of the company.

Functional analysis is a branch of mathematics that studies the properties of functions in infinite-dimensional spaces.

I love mathematics.

We need to analyze that data.

I need to analyze this data.

He is conducting research on a new energy source.

He is researching about a new energy source.

This math problem requires an understanding of functions.