It is a big chore for one researcher to reproduce the analysis and computational results of another. I always thought the difficulty in reproducing other people's work had deep and human causes. Then one day, quite by accident, I discovered that this problem has a simple technological solution: illustrations (figures) in a technical document are made by programs and command scripts that along with required data should be linked with the document itself. The text file of the document should, for each figure or illustration, contain a pointer to the command script that made it. This is hardly any extra work for the author, but it makes the document much more valuable to readers who possess the document in electronic form because they are able to track down the computations that lead to the illustrations. They can change parameters, data, boundaries, subroutines, etc., much easier than they could starting from scratch with the paper publication.