deterministic algorithm

Definition: 
An algorithm whose behavior can be completely predicted from the input.

See also nondeterministic algorithm.

Note: That is, each time a certain set of input is presented, the algorithm gives the same results as any other time the set of input is presented. For algorithms with state, or that maintain information between inputs, "the input" means everything since the algorithm was started from an initial state.

There can be degrees of deterministic behavior. For instance, an algorithm that uses random numbers might not be considered deterministic. However if the "random numbers" come from a pseudo-random number generator, the behavior may be deterministic.