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Possible Mathematica 4.0 bug

  • To: mathgroup at
  • Subject: [mg30786] Possible Mathematica 4.0 bug
  • From: Christian Mikkelsen <chr_mikkelsen at>
  • Date: Wed, 19 Sep 2001 00:16:25 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

The following problem cost most of a mornings work and
I ended up attributing it to a bug but before I send
it off to Wolfram Research I'd like some comments.

I have a polynomial defined as

H[z_]= (1/z^6)
I)((0.07806788263644916+0.9898486037537829 I)+I
I)+z)((0.7411819790476893+0.15538114678579676 I)+z));

with some auxiliary definitions 

f[w_] = Arg[H[Exp[I w]]];
fmm[w_] = (f[w+h]-2f[w]+f[w-h])/h^2 /.h->10^(-6) //
d = 1 10^8;

The following results in an erroneous(?)

disp[l_]=fmm[d/l] //Simplify

but defining d = 1.0 10^8 gives the correct(?) result.
A different result at any rate. Ok, so in principle I
have a workaround but I would be happy to know if the
issue also exists in version 4.1. I don't currently
have access to 4.1 but I am working on that.

Finally, it is of course possible that I have missed
something so I would be most happy to get feedback on
that as well.


Christian Mikkelsen

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