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MathGroup Archive 2005

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Re: LegendreP -- up to which order?

  • To: mathgroup at
  • Subject: [mg53591] Re: LegendreP -- up to which order?
  • From: "A. E. Siegman" <siegman at>
  • Date: Wed, 19 Jan 2005 02:00:02 -0500 (EST)
  • Organization: Stanford University
  • References: <cscicl$5lp$> <csiou4$np4$>
  • Sender: owner-wri-mathgroup at

I did a lengthy calculation once involving Legendre and other 
polynomials of high order (up in the 60s) and got remarkably accurate 
results (IMHO, anyway).

However I discovered that it made an observable difference at high 
enough orders whether the arguments were integers or reals.  If the 
arguments were reals I could see observable differences between the 
results from two calculations that should theoretically have given 
identical results; but if I entered an argument of 1.001 Pi in the form
1001 Pi/1000, for example, the results of the two alternative 
calculations would agree exactly.

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