Built-in functions for Complex numbers: 

We know that in MATLAB both i and j are built-in functions which return √-1 (therefore, they can be thought of as built-in constants). The Complex numbers can be generated by using i or j, for illustration, 5 + 2i or 3 - 4j. The multiplication operator is not needed between the value of the imaginary part and the constant i or j.

The MATLAB also has a function complex which will return a complex number. It receives two numbers, that is the real and imaginary parts in that order, or only one number that would be the real part (therefore the imaginary part would be 0). Here are a few illustrations of generating complex numbers in a MATLAB:

>> z1 = 4 + 2i

z1 =

   4.0000 + 2.0000i

>> z2 = sqrt(-5)

z2 =

   0 + 2.2361i

>> z3 = complex(3,-3)

z3 =

   3.0000 - 3.0000i

>> z4 = 2 + 3j

z4 =

   2.0000 + 3.0000i

>> z5 = (-4) ^ (1/2)

ans =

   0.0000 + 2.0000i

>> myz = input('Enter a complex number: ')

Enter a complex number: 3 + 4i

myz =

   3.0000 + 4.0000i

Note that even when j is used in an expression, i is used in the outcome. The MATLAB displays the type of the variables generated here in the Workspace Window (or by using whos) as double (complex). The MATLAB has functions real and imag which return the real and imaginary parts of complex numbers.

>> real(z1)

ans =

   4

>> imag(z3)

ans =

   -3