I want to select positive solutions to
Solve, but as the sign of the solutions depend on the value of some parameters/other variable, I am not sure how to do this?
For example, how do I select the positive solution of $x^2=a^2$ given that
a is positive? My code below doesn't work...
sol=Solve[x^2==a^2,x] Select[sol, (x/.#)>0&]
Also, could I have specified this directly in the Solve function, solving only for x positive knowing that a is positive?