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Re: good list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125126] Re: good list
  • From: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>
  • Date: Thu, 23 Feb 2012 05:45:20 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi to all,


I have a function  myfunc[x] (of some complexity) and I want to build
the list of its values in the interval (a<=x<=b) with step
dx=(b-a)/nstep


nstep=100;

mylist=Table[{x,myfunc[x],{x,a,b,(b-a)/nstep}];


According to the input value, sometimes myfunc[x] is not able to give a
numeric result

(in my case a singular difficult numerical integral) . In others cases
it works fine.

My question is how to build the list with only the good cases.


Many thanks, Roberto

Hi, Roberto,

Try this:

myFunc[x_]:=NIntegrate[Exp[-x*y^2],{y,0,\[Infinity]}]//Quiet;

Select[Table[{x,If[NumericQ[myFunc[x]]//Quiet,myFunc[x]]},{x,-1,1,0.1}],#[[2]]=!=Null&]
{{5.55112*10^-17,1.18945*10^8},{0.1,2.8025},{0.2,1.98166},{0.3,1.61802},{0.4,1.40125},{0.5,1.25331},{0.6,1.14411},{0.7,1.05924},{0.8,0.990832},{0.9,0.934165},{1.,0.886227}}

Have fun, Alexei
Alexei BOULBITCH, Dr., habil.
IEE S.A.
ZAE Weiergewan,
11, rue Edmond Reuter,
L-5326 Contern, LUXEMBOURG

Office phone :  +352-2454-2566
Office fax:       +352-2454-3566
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e-mail: alexei.boulbitch at iee.lu<mailto:alexei.boulbitch at iee.lu>




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