A
nomogram (from
Greek νόμος
nomos, "law" and γραμμή
grammē, "line"), also called a
nomograph,
alignment chart or
abaque, is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a function. The field of nomography was invented in 1884 by the French engineer
Philbert Maurice d’Ocagne (1862-1938) and used extensively for many years to provide engineers with fast graphical calculations of complicated formulas to a practical precision. Nomograms use a parallel
coordinate system invented by d'Ocagne rather than standard
Cartesian coordinates.