help on using maxima to solve systems of equations



Hi Tom,
   Not sure if someone already answered your question, but replacing (%i3)
by 'trigsimp(solve([e1,e2],[x,y]));' will effect the simplification you
want.
George Leeman

-----Original Message-----
From: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu]
On Behalf Of Tom Torfs
Sent: Friday, January 25, 2008 3:00 AM
To: maxima at math.utexas.edu
Subject: Re: [Maxima] help on using maxima to solve systems of equations
...
I have another question (again a simplified example):

(%i1) e1:x2=x*cos(phi)-y*sin(phi);
(%o1) x2=cos(phi)*x-sin(phi)*y
(%i2) e2:y2=x*sin(phi)+y*cos(phi);
(%o2) y2=cos(phi)*y+sin(phi)*x
(%i3) solve([e1,e2],[x,y]);
(%o3)
[[x=(sin(phi)*y2+cos(phi)*x2)/(sin(phi)^2+cos(phi)^2),y=-(sin(phi)*x2-cos(ph
i)*y2)/(sin(phi)^2+cos(phi)^2)]]

How can I get Maxima to recognize that sin(phi)^2+cos(phi)^2 = 1 ? Without
this type of simplification, the solutions of my system will get huge and
ugly. 

greetings,
Tom