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[bugs #7123] Bad results for QuadCurve2D.solveQuadratic

From: Sascha Brawer
Subject: [bugs #7123] Bad results for QuadCurve2D.solveQuadratic
Date: Wed, 7 Jan 2004 15:36:37 +0100

Summary:  Bad results for QuadCurve2D.solveQuadratic
URL: <>

Original Submission:  The method java.awt.geom.QuadCurve2D.solveQuadratic
sometimes does not return the right results for the following equation:

  (x^2)/10 + 20x + 1000 = 0

Expected result: -100

This equation is tested by Mauve; see

The problem occurs with various versions of gcj, compiling for IA-32.
However, it does NOT occur when executing the same Mauve testlet on
jamvm, using the same implementation for java.awt.geom.QuadCurve2D.

It turned out that a small Java test program for computing the equation's
discriminant gives a very small negative number when run on gcj/IA-32,
but exactly zero when run on jamvm or the Sun J2SE 1.4.1_01.

Follow-up Comments

Date: Wed 01/07/04 at 14:15         By: brawer
The problematic equation has been re-formulated as a test case for the
test suite of the GNU Scientific Library. It fails there, too.

See the attached e-mail to Brian Gough <address@hidden>, author
of the GNU Scientific Library.

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