A nomogram, often known as a nomograph, alignment chart, or abaque, is a graphical calculating machine, a two-dimensional diagram designed to permit the approximate graphical computation of a mathematical operate. It usually consists of three or extra scales, calibrated and organized so {that a} straightedge, often called an index line or isopleth, crossing them at particular values on every scale, supplies the results of the specified calculation the place it intersects the output scale. A easy instance is a slide rule the place a logarithmic scale is used to multiply or divide numbers by bodily including or subtracting distances on the rule.
These instruments provided fast calculation options in fields the place digital calculators have been unavailable or impractical, taking part in a vital position in scientific, engineering, and navy contexts all through historical past. Their capability to deal with complicated equations with a number of variables, offering speedy visible suggestions on relationships between them, provided a major benefit. Whereas largely outdated by digital know-how, nomograms stay helpful for understanding practical relationships and as academic instruments in visualizing mathematical ideas.
