If a polar diagram is mapped on to a cartesian coordinate system it is conventional to measure angles relative to the positive "x"-axis using a counterclockwise direction for positive angles. The magnitude of a complex number is the length of a straight line drawn from the origin to the point representing it. The Smith chart uses the same convention, noting that, in the normalised impedance plane, the positive x-axis extends from the center of the Smith chart at formula_66 to the point formula_67. The region above the x-axis represents inductive impedances (positive imaginary parts) and the region below the -axis represents capacitive impedances (negative imaginary parts).