Alexsander,
However the solution for a cubic is not difficult - Cardano's formula is
standard explicit method.
I implemented some years ago - although I cant find my source at the moment.
:-(
I suggest you do a web search for "Cubic" and "Cardano" (and "Fortran").
Several standard maths libraries have it, such as c02alc in the NAg
libraries and also Numerical Recipes, but I guess you want open source.
Hopefully someone else can post some source code?
Yours,
Daniel.
--------------------------------------------------------------
Dr. Dan Kidger, Quadrics Ltd. [log in to unmask]
One Bridewell St., Bristol, BS1 2AA, UK 0117 915 5505
----------------------- www.quadrics.com --------------------
-----Original Message-----
From: Aleksandar N. Donev [mailto:[log in to unmask]]
Sent: 17 February 2003 15:15
To: [log in to unmask]
Subject: Quartic equations
Hello,
Does someone have a routine for a quartic polynomial root solver? I need
to find the smalles real positive root of a quartic polynomial or know
that it does not exist. In cases when it does exist, it is likely that I
have a very good initial guess just by solving the corresponding quadratic
equation (ignoring two terms, since they are small!), but simply deciding
whether there is a positive real root seems hard (Sturm sequences?). The
code will be used in public-domain libraries.
Any advice from the experiences appreciated.
Snowed-In Aleksandar
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