Reversing an polynomial equation y = f(x) to x = f(y)
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回答 (2 件)
Walter Roberson 2012 年 5 月 13 日
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 2017 年 11 月 1 日
@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.