So, I have my function, such as
This function enters a big expression that contains variables x and y, as well as the function f. Now I have to differentiate that expression with respect to either x or y (or both). Evaluating the result, Mathematica will substitute each occurrence of f[x,y] with the definition above. For this particular function, its derivative will involve the factor of
When simplifying the result, how can I tell Mathematica to use this fact? I know there options to Simplify like TransformationFunctions, ExludedForms, ComplexityFunction, but the information and examples of the beginner-level on these options are rather scarce.
I think first I should have asked a simpler question.
In:= Simplify[G m/r^2, G m == A] Out= A/r^2
In:= Simplify[G m/r^2, G m/r^2 == A] Out= G m/r^2
Why is output not simply A?