Nomogram

nomogram, also called nomograph, calculating chart with scales that contain values of three or more mathematical variables, widely used in medicine, engineering, industry, and the biological and physical sciences.

In the most common form, a nomogram consists of three parallel graduated lines, known values on any two scales determining a straight index line (transversal) that passes through the solution value on the third. Some chart forms employ one or more curved graduated lines; or if straight, they may be arranged in the shape of the letter N.