Among many computer scientists, fortran is an f-word. yet, it's still the most widely used language in scientific computing, especially when high performance is required. why is this so? One explanation often given is the huge amount of scientific legacy code in the world-after all, differential equations remain the same over time and so do their solvers, so there's no reason to rewrite such code. But a great deal of new code is written in Fortran95 as well. One of us recently served on a review panel for granting computer time to high-impact scientific computing applications that effectively use thousands of processors, and every single one of the applications he reviewed was written in Fortran. At last year's conference on computational physics in South Korea (CCP2006), most of the plenary speakers who talked about codes used Fortran. Perhaps scientists prefer Fortran because they're productive when using it.