[Maxima] Solving "identification" problems
l.butler at ed.ac.uk
Sun Nov 8 13:22:47 CST 2009
On Sun, 8 Nov 2009, Leo Butler wrote:
< On Sun, 8 Nov 2009, Ulf Ekström wrote:
< < Dear all,
< < I am trying to make Maxima identify terms for me, for example
< < solve(x*y=a*(x+y)^2+b*(x-y)^2,[a,b]);
< < which I would like to give me a=1/4, b=-1/4. However, it seems that solve()
< < is not really made for this kind of equations. Is there any other function
< < I can use for these problems?
< < Sincerely,
< < Ulf Ekström, VU University Amsterdam
< <  I get: [[a=-(%r3*y^2+(-2*%r3-1)*x*y+%r3*x^2)/(y^2+2*x*y+x^2),b=%r3]]
< The output from solve is correct, but you are looking for a & b as
< coefficients. Here are a couple ways to do this:
< eq : x*y = a*(x+y)^2+b*(x-y)^2;
< eq : rat(x*y - a*(y+x)^2+b*(x-y)^2);
eq : rat(x*y - a*(y+x)^2-b*(x-y)^2);
for your example.
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