MuPAD - rearrange an equation

Question

I have a huge expression, say $f(x_1,x_2,x_3) = 0,$ and I want MuPAD to try to express $x_1 $ in terms of $x_2$ and $x_3$ Is this possible?

Answer 1

You can try using solve, which is a general solver for symbolic equalities and inequalities. Here's an example:

f:=x1^2+x2^2+x3^2=0
solve(f,x1)

which returns two solutions, as expected:

{-(- x2^2 - x3^2)^(1/2), (- x2^2 - x3^2)^(1/2)}

This may ore may not work for your equation that you didn't provide. I recommend reading the documentation for solve carefully, trying the examples, and learning about the various options.

MuPAD's solve is very similar to the solve available directly within Matlab's symbolic Math toolbox (see documentation here). So you could also solve the above example via:

syms x1 x2 x3
f = x1^2+x2^2+x3^2==0
solve(f,x1)