Matlab implementation of an algorithm that generates all restricted integer compositions of an integer n with k parts, each in the discrete interval [a,b].
The algorithm is based on
Vincent Vajnovszki, Generating permutations with a given major index, http://arxiv.org/abs/1302.6558
(Algorithm in Figure 2). The algorithm appears to be (much) faster than, e.g., the competing JD Opdyke algorithm for the same task.