Solving symbolic equation with additional assumptions

My question is somehow related to this topic: http://www.mathworks.com/matlabcentral/answers/322874-how-to-calculate-eigensystem-of-symbolic-matrix-with-orthogonal-elements

Once again, lets assume simple symbolic equation:

syms a b

solve(a+a.*b==2)

also, lets assume that a.*b is always ==0; so the solution of the eq is supposed to be a=-2; How can I implement such assumption (a.*b==0) into matlab code? Any help appreciated!

Answer 1

[Torsten]

syms a b 
[sola, solb] = solve([a+a*b == 2, a*b == 0], [a, b])

Best wishes

Torsten.

[Pawel Rochowski]

Hi Torsten, after passing your code to matlab (2014a) I'm getting a massage:

Warning: 4 equations in 2 variables. > In C:\Program Files\MATLAB\R2014a\toolbox\symbolic\symbolic\symengine.p>symengine at 56 In mupadengine.mupadengine>mupadengine.evalin at 97 In mupadengine.mupadengine>mupadengine.feval at 150 In solve at 170 Warning: Explicit solution could not be found. > In solve at 179 sola = [ empty sym ] Am I missing something?

[Torsten]

You will have to consult the 2014a documentation on how to use "solve" for your MATLAB version.

For the recent version, the syntax is as stated:

https://de.mathworks.com/help/symbolic/solve.html

Best wishes

Torsten.