Reversing an polynomial equation y = f(x) to x = f(y)
109 views (last 30 days)
Walter Roberson on 13 May 2012
polynomials of degree 2 or higher cannot be inverted to give a polynomial.
The inverse of the particular polynomial you indicate is the union of three expressions.
If you have the symbolic toolbox, you can use solve()
Marcin Konowalczyk on 1 Nov 2017
@Walter is right, but what you can do is approximate them using, for example, this function. This works only in a small domain where your polynomial is well conditioned (monotonically increasing) and fails horribly otherwise, but for certain cases (see the docstring of the linked function) it is useful.