Don't knock it! Using a functional language helped you to think about the problem in a new way, and throw together a prototype that worked in a short enough time that you actually did it. A merit of fp is, I think, that you can explore the algorithm design space much more quickly -- and algorithms are the dominant factor in the performance equation. Simon | -----Original Message----- | From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Seth | Gordon | Sent: 15 November 2006 20:49 | To: haskell-cafe@haskell.org | Subject: Re: [Haskell-cafe] the case of the 100-fold program speedup | | As Lily Tomlin would say, neVERmind. | | Simon P-J asked me, in email, whether the deforestation was the thing | that actually made the program faster or whether it was just the thing | that made me think about how to solve the problem. I realized that my | fast program had *another* difference from the earlier, slower program: | it was based on an algorithm that was specifically designed to clip | polygons to rectangles, whereas OGR just had a function to compute the | intersection between two arbitrary polygons. | | So I threw together a version that accumulated all the vertices of the | clipped polygon in a list and then iterated through the list to compute | the centroid--i.e., preserving everything from my fast program except | the deforestation--and it ran at almost exactly the same speed as the | deforested program. (Actually, it ran 2% faster, but that could be just | random variation from things like the load on the database server.) | | "The tragedy of science: a beautiful theory slain by an ugly fact." | | "T. H. Huxley said it first." | _______________________________________________ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe