nomograph

nom·o·graph (nŏmʹə-grăf', nōʹmə-) or nom·o·gram (-grăm') n.

1. A graph consisting of three coplanar curves, each graduated for a different variable so that a straight line cutting all three curves intersects the related values of each variable.

2. A chart representing numerical relationships.

  [Greek nomos, law; See nem- in Indo-European Roots + -graph.]   nom'o·graphʹic adj. no·mogʹra·phy (nō-mŏgʹrə-fē) n.

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▪ mathematics

also called  Alignment Chart,  

      calculating chart with scales that contain values of three or more mathematical variables, widely used in engineering, industry, and the natural and physical sciences.

      In the most common form, a nomograph 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.

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