Tried out my own Laguerre implementation from here: https://github.com/mlochbaum/bqn-libs/blob/master/polynomial.bqn#L80-L113
I remember I used J as a reference for this, but I think I ended up following this one in Julia: https://github.com/giordano/PolynomialRoots.jl/blob/master/src/PolynomialRoots.jl#L255 With the starting point at 0 it converges, but only with a few random adjustments from this line: { 0=jump_i|i ? root +↩ dx × Jump i÷jump_i ;@} Here Jump i÷jump_i just ignores the argument and produces a random float, ?0 in J (Julia has a table to avoid computing one). Removing this, I see a small region of non-convergence around 0, radius between 0.1 and 0.2. I suppose this isn't what you get? Marshall On Sat, Feb 04, 2023 at 08:34:46PM -0500, Henry Rich wrote: > Somehow I lost the original post. > > For some reason Laguerre's method doesn't converge for this polynomial. > There seem to be large regions of non-convergence. Changes of up to 1e_5 in > any of the constants still fail to converge. > > The point seems to oscillate in a wide range but doesn't head toward any > solution. In the implementation the initial guess is always 0j0. > > I don't see why this would fail. If anyone on this list can help, or knows > someone who can help, I'd appreciate suggestions. > > Henry Rich > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
