A complex number is composed of two parts, or components—a ''real'' component and an ''imaginary'' component. Each of these components is an ordinary (that is, real) number. The complex numbers form an "extension" of the real numbers: If the imaginary component of a complex number is zero, that number is essentially identical to the real number that is its real component. | A complex number is composed of two parts, or components—a ''real'' component and an ''imaginary'' component. Each of these components is an ordinary (that is, real) number. The complex numbers form an "extension" of the real numbers: If the imaginary component of a complex number is zero, that number is essentially identical to the real number that is its real component. |