cray instability

cray | = C = | crayola

cray instability n.

1. A shortcoming of a program or algorithm that manifests itself only when a large problem is being run on a powerful machine (see cray). Generally more subtle than bugs that can be detected in smaller problems running on a workstation or mini. 2. More specifically, a shortcoming of algorithms which are well behaved when run on gentle floating point hardware (such as IEEE-standard or PDP-series machines) but which break down badly when exposed to a Cray's unique `rounding' rules.

cray | = C = | crayola