Today's bugs

[Alexander Frink]

On Mon, 21 Feb 2000, Richard B. Kreckel wrote:
> The other bug is with the fraction free elimination in ginac/matrix.cpp:
> If I try to solve the system 
> [[ [[0,2-a]], [[5-4*a,3+2*a]] ]] * [[ [[x]], [[y]] ]] 
>                           == [[ [[-2+5*a]], [[-5-2*a]] ]]

Looks like the reason is a problem in normal():

    symbol a("a");
    ex z=((-5-2*a)-((2-5*a)/(-2+a))*(3+2*a))/(5-4*a);
    cout << "z=" << z << endl;
    cout << "normal(z)=" << normal(z) << endl;

z=(5-4*a)^(-1)*(-5-2*a-(3+2*a)*(2-5*a)*(-2+a)^(-1))
normal(z)=-(5-4*a)^(-1)*(-22+2*a*(-2+a)-10*a^2)*(-2+a)^(-1)

-- 
Alexander Frink                      E-Mail: Alexander.Frink at Uni-Mainz.DE
Institut fuer Physik                 Phone:  +49-6131-3923391
Johannes-Gutenberg-Universitaet
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