ASKSAGE: Sage Q&A Forum - Individual question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Tue, 12 Jun 2012 03:49:54 -0500separation of variables / parameterizing equations in sage mathhttp://ask.sagemath.org/question/9054/separation-of-variables-parameterizing-equations-in-sage-math/<p>Hi,</p>
<p>I've sometimes run into the situation where sage math is unable to solve a system of equations that I then rearrange and am subsequently able to solve.
The question is, Is sage able to do this re-arranging itself?
</p>
<p>Example:</p>
<p>Given a contraint eq1, and eq2 for an op amp subtractor that mixes variables together </p>
<code>
eq1 = vout == (2*v1 - 3*v2)
</code>
<br>
<code>
eq2 = vout == (v1*(R4/(R3+R4))-(((v2-(v1*(R4/(R3+R4))))/R1)*R2))
</code>
<p>can sage somehow rewrite this as an parameterized equation
in terms of v1 and v2</p>
<code>
eq2 = vout == v1*( (R4/(R3+R4)+((R4/(R3+R4))/R1)*R2)) + v2*((-1/R1)*R2)
</code>
<p>
Without my manual intervention?</p>
<p>
I'd like to know if sage can detect that
<p>
2 == ( (R4/(R3+R4)+((R4/(R3+R4))/R1)*R2))
and -3 == ((-1/R1)*R2)
</p>
and solve those.
</p>
<p>
Can it also automatically detect if an equation can be safely separated in this way along some given variables??
</p>
<p>
Thanks to anyone who tries to answer this!
</p>Sat, 09 Jun 2012 16:56:41 -0500http://ask.sagemath.org/question/9054/separation-of-variables-parameterizing-equations-in-sage-math/Comment by bk322 for <p>Hi,</p>
<p>I've sometimes run into the situation where sage math is unable to solve a system of equations that I then rearrange and am subsequently able to solve.
The question is, Is sage able to do this re-arranging itself?
</p>
<p>Example:</p>
<p>Given a contraint eq1, and eq2 for an op amp subtractor that mixes variables together </p>
<code>
eq1 = vout == (2*v1 - 3*v2)
</code>
<br/>
<code>
eq2 = vout == (v1*(R4/(R3+R4))-(((v2-(v1*(R4/(R3+R4))))/R1)*R2))
</code>
<p>can sage somehow rewrite this as an parameterized equation
in terms of v1 and v2</p>
<code>
eq2 = vout == v1*( (R4/(R3+R4)+((R4/(R3+R4))/R1)*R2)) + v2*((-1/R1)*R2)
</code>
<p>
Without my manual intervention?</p>
<p>
I'd like to know if sage can detect that
</p><p>
2 == ( (R4/(R3+R4)+((R4/(R3+R4))/R1)*R2))
and -3 == ((-1/R1)*R2)
</p>
<p>and solve those.
</p><p></p>
<p>
Can it also automatically detect if an equation can be safely separated in this way along some given variables??
</p>
<p>
Thanks to anyone who tries to answer this!
</p>
http://ask.sagemath.org/question/9054/separation-of-variables-parameterizing-equations-in-sage-math/?comment=19621#post-id-19621I'd've recommend You to read 'symbolic expression' of reference manual. Take a look at `collect`, lhs(), rhs() there.Tue, 12 Jun 2012 03:49:54 -0500http://ask.sagemath.org/question/9054/separation-of-variables-parameterizing-equations-in-sage-math/?comment=19621#post-id-19621