Re: Problem with the Gaussian Quadrature package
- To: mathgroup at yoda.physics.unc.edu
- Subject: Re: Problem with the Gaussian Quadrature package
- From: keiper
- Date: Fri, 27 Aug 93 18:19:58 CDT
> There also seems to be a problem with large n. ...
> Where does 0000. come from?
When numbers are so imprecise that not even the first digit is known
they are printed as an inexact zero in a way that indicates the amount
of imprecision. Thus "0000." indicates that the imprecision is about
10^4, while ".000" indicates that the imprecision is about 10^-3.
There are ways to calculate the Gaussian coefficients without a great
deal of precision loss, but it is not an easy problem. (The internal
code for NIntegrate[ ] does this, but it is a fair bit of code.)
The Gaussian Quadrature package is intended as much for instructional
purposes as anything else so I decided to implement it in a way that
was most easy to understand even though it is not the most numerically
stable approach. The idea is that the user can always increase the
precision to get the required precision in the results.
Jerry B. Keiper
keiper at wri.com
Wolfram Research, Inc.