Simplex may refer to: Mathematics Simplex, a term in geometry meaning an n-dimensional analogue of a triangle Pascal's simplex, a version of Pascal's triangle of more than three dimensions Simplex algorithm, a popular algorithm for numerical solution of linear programming problems Simplex graph, derived from the cliques of another graph Simplex noise, a method for constructing an n-dimensional noise function Simplex plot, a ternary plot used in game theory Companies and trade names Simplex (bicycle), a French bicycle derailleur brand Simplex Manufacturing Corporation, an American manufacturer of motorcycles in Louisiana from 1935 to 1975 American Simplex, an American automobile made in Mishawaka, Indiana, US Simplex Automobile Company was a defunct luxury car manufacturer from 1907 to 1921. Crane-Simplex, a defunct luxury car manufacturer in New York, US at the start of the 20th century Sheffield-Simplex, a British vehicle manufacturer operating 1907–1920 Simplex Typewriter Company, an index typewriter manufacturer A trade name used by British railway locomotive manufacturers The Motor Rail & Tramcar Co Ltd The trade name of the swinging-tray record changer used in Wurlitzer jukeboxes from the 1930s to the 1950s A brand of fire alarm systems made by SimplexGrinnell A manufacturer of jacks used in railroads and mining industries, now owned by Actuant Corporation Technology Bergmann Simplex, an early 20th-century, German-made handgun Simplex communication, a one-way communications channel Simplex signaling, signalling in which two conductors are used for a single channel Simplex, using a single frequency for transmit and receive instead of an amateur radio repeater SimpleX Messaging Protocol, a privacy focused messaging protocol Small Innovative Missions for Planetary Exploration (SIMPLEx) program at NASA; see Lunar Polar Hydrogen Mapper and Q-PACE Other uses List of species named simplex, a common species name Mercedes Simplex, an automobile model produced between 1902 and 1909 Herpes simplex, a viral disease caused by Herpes simplex viruses Simplex printing, printing one sided pages, a technique that is contrast to duplex printing