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MathGroup Archive 2005

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Re: Switching to Mac caused 20x slowdown - please help!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg60286] Re: [mg60275] Switching to Mac caused 20x slowdown - please help!
  • From: Selwyn Hollis <sh2.7183 at earthlink.net>
  • Date: Sat, 10 Sep 2005 06:46:37 -0400 (EDT)
  • References: <200509090807.EAA16024@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

That runs in about 0.01 seconds on my Dual 2.5GHz G5, which doesn't  
make much sense compared to either of your timings. But I have two  
suggestions:

1) Open your Energy Saver preference pane, click on Options, and set  
processor performance to Highest.

2) Try using Compile to speed up your code.

Regards,

Selwyn Hollis
http://www.appliedsymbols.com
http://www.math.armstrong.edu/faculty/hollis




On Sep 9, 2005, at 4:07 AM, flatuniverse wrote:

> Hello All,
>
> I'm having a major speed problem in moving from Linux to Mac.
>
> Old machine: Dell Inspiron 8100 - 1GHz Pentium 3, 512MB RAM - Linux
> RedHat - Mathematica 5
> New Machine:  Apple Powerbook - 1.3GHz G4, 512MB RAM - OS 10.4.2 -
> Mathematica 5.2
>
> The bit of code below, which I need to loop many many times, is now
> taking about 20 times longer - from ~.01 sec in Linux to ~.2 sec in
> OSX.  The lag seems to be in the first function, "newh2" which I admit
> is probably implemented very poorly.  I tried simpler versions using
> "If" and "Piecewise," but that caused the second function  
> "magFromq" to
> fail.  Can anyone speed up this code?
>
> Thank you very much!
>
>
> H0 = 3.335*^-10 ;
>
> \!\(\(newh2[
>     z_?NumberQ, dq_, dz_, z1_, Om_:  .28] := Module[{h2temp, qmodify,
>         z2}, \[IndentingNewLine]z2 =
>        z1 + dz; h2temp = Om*\((1 + z)\)\^3 + \((1 - Om)\); \
> \[IndentingNewLine]qmodify = \((\(1 +
>         z\)\/\(1 + z1\))\)\^\(2  dq*\((UnitStep[z - z1] -
>            UnitStep[z - z2])\)\)\ *\((\(1 + z2\)\/\(1 +
>               z1\))\)\^\(2  dq*UnitStep[z -
>         z2]\); \[IndentingNewLine]h2temp *=
> qmodify\[IndentingNewLine]];\)\)
>
> \!\(\(magFromq[z_?NumberQ, dq_:  0, dz_:  .01, z1_:
>         99, Om_:  .28, h_:  .717137] := 5  Log[10, \((1 + z)\)\/\(10
>          h*H0\)\ NIntegrate[1\/\@newh2[x, dq, dz, z1, Om], {x, 0,
> z}]];\)\)
>
> magFromq[2,.05,.05,1]//Timing
>
> {0.235472 Second,45.9423}
>
>


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