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Re: Where's the Speed?

  • To: mathgroup at
  • Subject: [mg19783] Re: Where's the Speed?
  • From: Jens-Peer Kuska <kuska at>
  • Date: Fri, 17 Sep 1999 01:36:40 -0400
  • Organization: Universitaet Leipzig
  • References: <7rnklm$>
  • Sender: owner-wri-mathgroup at

Hi Kevin,

I assume a unfortunate implementation. The speed gain is visible
and between a factor of 5 to 20.

Send me the source and I will take a look on it. 
You can still have my 1D and 2D Schr"odinger solver 
in MathLink with open boundaries. It should give you the result with a
delay of 4-5 seconds even on a 100 MHz 486.
Even the 2d version with 256 x 256 mesh points need only 30 seconds
on a modern PC.

Hope that helps

"Kevin J. McCann" wrote:
> I have read and heard a lot of hype about Mathematica 4.0
> "featuring a
>      New Generation of
>                     Fast Numerics"
> e.g. on .
> 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?

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