Where's the Speed?
- To: mathgroup at smc.vnet.net
- Subject: [mg19764] Where's the Speed?
- From: "Kevin J. McCann" <kevin.mccann at jhuapl.edu>
- Date: Wed, 15 Sep 1999 03:53:10 -0400
- Organization: Johns Hopkins University Applied Physics Lab, Laurel, MD, USA
- Sender: owner-wri-mathgroup at wolfram.com
I have read and heard a lot of hype about Mathematica 4.0 "featuring a New Generation of Fast Numerics" e.g. on www.wri.com . However, in the real world it is hard to find anything to get excited about. I have had several disappointing results from 4.0, here are the latest: On a P450/NT I ran a very simple Crank-Nicholson integration of a one-dimensional quantum free-particle wave-packet with x-dimensioned to 1001 points and time to 401 points - no error checks or adaptive stepsize, just plug-and-chug. Runtime under 4.0 was 501 seconds, 3.0 was 480 seconds, but who's quibbling; however, in FORTRAN this ran in 8 seconds. I don't even consider this to be "fast numerics", but 501 seconds sure isn't. I would like to know where all this speed is so I can use some of it, or am I missing something? When I ran the FORTRAN code and then read it into Mathematica, it still was faster than the Mathematica code alone, although the ReadList I used on the ASCII file did take some time. When I upped the dimensions to 2001 x 1001, the FORTRAN ran in about 40 s - most of this is for the output; however, when I tried to read it in to Mathematica, it took forever, and on the subsequent plot it bombed the Kernel. I then made the mistake of saving the NB which managed to acquire an error so that I can't open it anymore - 6 Mb of useless NB! -- Kevin J. McCann Johns Hopkins University APL