On Tue, Nov 11, 2008 at 9:22 AM EST, I wrote: > I think that's the wrong question. In this case, the right question > would have been "Is it an issue that we have twice as many > calculations as we need". And, the answer around here is > often that a factor of two is sometimes worth bothering with and > sometimes not. The "noise level" on a modern computer > is usually less than a factor of two speed difference on repeated > runs but can be significantly greater than a factor of two for the > first run,
I should add that there are bigger reasons why a factor of 2 is usually not very relevant. One of the reasons, of course, is that sometimes a factor of 2 can be relevant. This would be when that factor of 2 is on your critical path and depleting a bottleneck resource. However a bigger issue is that often re-architecting your system can give you a factor of 1000, or better, resource improvements. (For example, if a calculation is being run repeatedly, maybe you can lift some of the complexity out of the repeating aspect of the system.) Another, bigger, issue is that in the long run simplicity usually matters more than resource use. Not always, of course, but simplicity also helps you when you have identified your bottlenecks -- with a simple system you can often do fundamental rearrangements that would be much more expensive if you had spent a lot of time and complexity optimizing non-bottlenecked parts of your system. Finally, the biggest issue is correctness. If you optimize before your have your system doing the right thing, at best you have a fast way of doing the wrong thing. (Or, maybe you have a slow way of doing the wrong thing that has lots of fast and efficient subsystems.) -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
