ised is a command-line tool for generating number sequences and arithmetic evaluation. Unlike big GUI-based software (such as Mathematica, Derive, Matlab, or Octave), ised is intended for use in shell scripting, together with the GNU core utilities. Its main advantage is that all functions are generalized to operate on one-dimensional arrays. It can be used for loop indexing (much like seq), line-by-line arithmetic processing of files, floating point math for shells that don't support it natively, or interactive expression evaluation (i.e. as an extended calculator).