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Re: avoiding non-machine numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg115588] Re: avoiding non-machine numbers
• From: Achilleas Lazarides <achilleas.lazarides at gmx.com>
• Date: Sat, 15 Jan 2011 04:47:22 -0500 (EST)

I have this in my init.m:

switchCatchUnderflow[]:==(SetSystemOptions[CatchMachineUnderflow->#1]&)[!CatchMachineUnderflow/.SystemOptions[CatchMachineUnderflow]]

which flips the option indicated. I get:

In[65]:== Exp[-#^2] &@
   RandomReal[NormalDistribution[0, 20], 400000]; // Timing
switchCatchUnderflow[];
Exp[-#^2] &@RandomReal[NormalDistribution[0, 20], 400000]; // Timing

Out[65]== {1.62773, Null}

Out[67]== {0.12662, Null}

On Jan14, 2011, at 12:17 PM, wpb wrote:

>  t == RandomReal[NormalDistribution[0, 20], 400000];
> Exp[-t^2]; // Timing