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NIntegrate: <XXX> should be a machine-size complex number??.

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  • Subject: [mg19672] NIntegrate: <XXX> should be a machine-size complex number??.
  • From: Alessandro Simonetto <simonetto at ifp.mi.cnr.it>
  • Date: Thu, 9 Sep 1999 02:19:45 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

I'm stuck with strange messages from Mathematica.
I have ff[x,y] as the ListInterpolation of a Table of Complex numbers
e.g.
ff[x,y]=ListInterpolation[Table[E^((i+j)/20.*(I+1)),{i,1,51},{j,1,51}],{xx,yy}],
where xx,yy are the arrays of the x,y values.
(Of no use here, but the real problem is with a Table of my Complex data
measured at gridpoints {xx,yy}).
ff evaluates nicely to a Complex number as it should, but if I try

NIntegrate[ff[x,y],{x,xmin,xmax},{y,ymin,ymax},MaxPoints->25000]

I get the following series of messages:
General::dupsym:
   -- Message text not found -- (XXnn) (NIntegrate`Private`)
(repeated also for XXnn+1, where nn changes every time)
CompiledFunction::cccx:
   Expression InterpolatingFunction[{{-48., 102.}, <<1>>}, <<1>>][
     <<2>>] should be a machine-size complex number.
CompiledFunction::cfex:
   External evaluation error at instruction 4; proceeding with
     uncompiled evaluation.
After which it repeats the sequence a couple of times and writes back the
input.

I can't understand any of the messages. Especially the one complaining
about the function not evaluating to a Complex number, whereas it does.

Can you shed light on the question? I assume NIntegrate can handle Complex
numbers, otherwise it shoould complain about the numbers not being Real...
Thank you in advance
Alessandro

--
Alessandro Simonetto




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