What is "does not compute"

phr. that doesn't make sense

"Does not compute", and variations on it, is a phrase often spoken by computers, robots and other artificial intelligences in science fiction works of the 1960s to 1980s. The phrase indicated cognitive dissonance on the part of the device, conventionally leading to its self-destruction. The phrase "does not compute" and robots who self-destruct when considering emotions or paradoxes is frequently satirized in popular culture. The phrase was first used as a catchphrase by the television show My Living Doll in 1964. It was then popularised in Lost in Space (1965), along with "Affirmative!", "Warning! Warning!" and " Danger, Will Robinson!"

The phrase is rarely found in actual computing outside of humorous effect, but the problem of how to hold the result of a computation that is not a number is genuine (for example, 1/0) and represented a problem for early computers that would experience divide-by-zero errors or other mathematical paradoxes that software had not yet been written to deal with, leading to a computer crash. The NaN and related data types were invented to solve this problem.