[Scilab-users] result of spec function generate an error #144

[Dang, Christophe]

Hello,

I implemented the Fitzgibbon algorithm[1] for ellipse fitting. This algorithm extracts the eigenvalues and -vectors from a matrix, and therefore uses the spec function.

When I test the eigenvalue, e.g.
eigval > 0
I get an error message 144 "Undefined operation for the given operands."

I found a workaround
sign(eigval) == 1

But would like to understand why I get this message.
Did I do something wrong?
Is this a documented limitation?
Is this a bug?

Thanks in advance

[1] Halir, R. and Flusser, J., Numerically Stable Direct Least Squaes Fitting of Ellipses, in Winter School of Computer Graphics, vol. 6, 1998
http://wscg.zcu.cz/wscg1998/papers98/Halir_98.ps.gz

-- 
Christophe Dang Ngoc Chan
Mechanical calculation engineer

Sidel Group 
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