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Which library/libraries did you use for the interactive graphs?

Just JSXGraph: https://jsxgraph.uni-bayreuth.de/wp/index.html

I'm not entirely happy with the framerate I get with the button-triggered animations (especially on mobile) but lack the front-end expertise to track down the problem.

Would be nice if dragging the coefficients would also change the roots.

Yeah. I think I punted on that because, although it's easy for degrees <= 4 (since those have general formulas!), I'd have to implement some root-finding method for degrees >= 5, and somehow preserve the orderings of the roots. Not insurmountable problems -- I might go back and do that someday!

I was just pondering about this. I imagine that moving a coefficient a small amount (and so long as the roots are not too close) that Newton-Raphson, initialized with a previously-known root, would converge very quickly to the new root while preserving the order.

If there truly are roots of multiplicity >= 2, then preserving the order of the multiple roots doesn't matter. Another issue is that Newton-Raphson might fail if the roots are too close.

Ah, interesting, I had not heard of that one.

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