bet@ecsvax.UUCP (Bennett E. Todd III) (12/04/85)
Alan Wendt (wendt@arizona) has informed me that the Cubic program I
posted to net.sources a while ago doesn't always work. Some inputs
produce roots that just aren't. I don't know what's wrong; I'll try to
look at it. In the interim, please note that while the comments reflect
the algorithm (presumably correct) from CRC's Standard Math Tables, the
actual code doesn't seem to implement that algorithm exactly correctly.
In particular,
x^3 + 4x^2 + 4x + 1 = 0
Should at least have the trivial root x = -1; the cubic program gets it
wrong. My apologies; without a a complex number calculator I was too
lazy to really try it out sufficiently. Thanks to Alan for pointing this
out, I hope this hasn't inconvenienced anyone, and if anybody figures
out what's wrong please let me know.
-Bennett
--
"Hypocrisy is the vaseline of social intercourse." (Who said that?)
Bennett Todd -- Duke Computation Center, Durham, NC 27706-7756; (919) 684-3695
UUCP: ...{decvax,seismo,philabs,ihnp4,akgua}!mcnc!ecsvax!duccpc!betwendt@bocklin.UUCP (12/10/85)
A new version of Bennet Todd's program has been posted to net.sources. Alan Wendt arizona!wendt I'll stop breaking the law when they repeal it.