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FunctionInterpolation Q

  • To: mathgroup at
  • Subject: [mg14915] FunctionInterpolation Q
  • From: "Arturas Acus" <acus at>
  • Date: Wed, 25 Nov 1998 17:48:36 -0500
  • Sender: owner-wri-mathgroup at

Dear group,

Recently I have tried the following:

Re[NIntegrate[Exp[I*p*x]*Exp[-x^2], {x,1,Infinity}]],{p,0,3}]

with the only difference that insted of Exp[-x^2] I have used some my 
function. This is actually Fourier integral transformation of my
special function,  having non zero values in the interval [1,Infinity]
over the interval  {p,0,3}.

The following modification involving function "interm" works, if I 
specify the argument with (p_?NumberQ) (not just p)

interm[p_?NumberQ]:=Re[NIntegrate[Exp[I*p*x]*Exp[-x^2], {x,1,Infinity}]]
In[49]:= FunctionInterpolation[interm[p],{p,0,3}]

Could anybody explain what happens here. It seems for me to be an
evaluation order problem here.

But I want a single function. Also suggestions to speed up the 
transformation is wellcome.

                                      Arturas Acus
Institute of Theoretical
Physics and Astronomy
Gostauto 12, 2600,Vilnius

E-mail: acus at
   Fax: 370-2-225361
   Tel: 370-2-612906

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