Matlab: Real and imaginary parts of complex number and multiplication with imaginary unit j

For a complex number x = 1 + 2i or x = 1 + 2j

Matlab commands for real part - real(x)
Matlab commands for imaginary part - imag(x)

Example:

>> x = 1 + 2j

x =

   1.0000 + 2.0000i

>> real(x)

ans =

     1

>> imag(x)

ans =

     2

>>

To multiply x with an imaginary unit i or -i, simply swap the real part with the imaginary part and add a negative sign.

Example:

x = 1 + 2j

mult_pos_j(x)

mult_neg_j(x)

function result = mult_pos_j(x)

    % x = a + bj

    % x(j) = aj - b = -b + aj

    result = -imag(x) + real(x)*j;

end

function result = mult_neg_j(x)

    % x = a + bj

    % x(-j) = -aj + b = b - aj

    result = imag(x) - real(x)*j;

end

Result:

x =

   1.0000 + 2.0000i


ans =

  -2.0000 + 1.0000i


ans =

   2.0000 - 1.0000i

Related Information:

Complex numbers - simple calculations (StudySwift - iOS)