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MathGroup Archive 1999

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

  • To: mathgroup at smc.vnet.net
  • Subject: [mg19684] Re: NIntegrate: <XXX> should be a machine-size complex number??.
  • From: "Kevin J. McCann" <kevinmccann at Home.com>
  • Date: Sat, 11 Sep 1999 16:35:56 -0400
  • Organization: @Home Network
  • References: <7r7jjs$ciq@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Alessandro,

I am not sure about what you did in this statement:

>
ff[x,y]=ListInterpolation[Table[E^((i+j)/20.*(I+1)),{i,1,51},{j,1,51}],{xx,y
y}],
> where xx,yy are the arrays of the x,y values.

i.e., what is meant by "the arrays of x,y values."  xx and yy in your
expression should be the limits on the x and y variables.  Here is an
example:

In[1]: gg = ListInterpolation[
         Table[E^((i + j)/20.*(I + 1)), {i, 1, 51}, {j, 1, 51}], {{1, 51},
{1,
         51}}]

Out[1]:  InterpolatingFunction[{{1., 51.}, {1., 51.}}, "<>"]


Then

In[2]: NIntegrate[gg[x, y], {x, 1, 51}, {y, 1, 51}]

Out[2]: -33124.96551224837 - 17234.035867321498*I

Hope this helps.

Kevin

Alessandro Simonetto <simonetto at ifp.mi.cnr.it> wrote in message
news:7r7jjs$ciq at smc.vnet.net...
> 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,y
y}],
> 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:

< snip>




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