Introduction

Complex numbers have a real part and an imaginary part. e.g.

For 2+7i, the real part:  Re(2+7i) = 2  and the imaginary part:  Im(2+7i) = 7.

Cartesian Form

Generally we denote a complex number by z, as follow:

z = a + ib

Where a and b are real numbers, they belong to the set of real numbers i.e. a,b .

(The set of complex numbers is denoted by .)

Now Re(z) = a  and  Im(z) = b, so you can see if b=0 we have a real number and if a=0 we have an imaginary number.