Complex numbers can be shown on a so-called complex plane. If you have a number formula_14, you can go to point "a" on the real axis and point "b" on the imaginary axis, and draw a vector from formula_40 to formula_41. The length of this vector can be calculated using the Pythagorean theorem, and the angle of this vector is simply the angle between the positive real axis and this vector—going counterclockwise. The length of a vector for a number formula_13 is called its modulus or absolute value (written as formula_43), and the angle is called its argument (formula_44).