Edwin Woollett wrote:
> Maxima by Example, Ch. 12, Dirac Algebra
> and Quantum Electrodynamics update Jan. 10, 2011.
Hi, Edwin
i have just looked at your manuals, and noted a problem i remarked recently,
that you may have not noted in your Chapter 9, use of bfallroots.
The problem is that if you feed a polynomial with bfloat coefficients (*)
to bfallroots, to get the solution, the first thing it does is to convert
all coeffs to rats, and does that with small precision (something like
eight digits), so you can set fpprec=30 as much as you want the solutions
are not correct to more than 7 digits.
The solution is to also set ratepsilon=30 before beginning the computation,
then you get roots correct to around 30 figures. If this appears somewhere
on your paper i have not seen, please excuse my post.
By the way, your Chapter 12 is really magnificent.
(*) the example i had was with finding roots for a Bethe ansatz, the
polynomials really has coefficients with a lot of digits, there are huge
order of magnitudes between coeffs, still bfallroots finds correct results
--
Michel Talon