Question 223663 in Mysql Question posted in
The official MySQL documentation can be found here.

Calculate roots of polynomial in MySQL

I current use the numpy roots function as follows:

y = numpy.roots([-2, 3, 0, -1 * x])[1]

In the above x is a column in a table that I extract to run through the function.

If possible I’d like to move this into a MySQL query. I’ve tried replicating the nuts and bolts of the function but quickly got lost when I got to eigenvalues.

I’m not even close to being a mathmatician so I’m wondering if anyone here has attempted this?

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2

Answers


  1. 0

    Since MySQL is primarily designed for database operations, calculating the roots of a polynomial directly in a MySQL query does not seem very practical. Although, by using a SLF(Server Loadable Function) this should allow you to write a custom function in a another language like C or C++, then integrate said function into MySQL.

    Read more about SLF
    Here
    Or
    Here

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  2. 0

    For polynomials of small order, you might be able to do it simply by using the general solution formulas. Order 1 is trivial, order two uses the good old quadratic formula we were all taught at school. Your example appears to be cubic polynomial. There is a general formula for the roots of

    ax^3 + bx^2 + cx + d = 0

    given by (courtesy of Wikipedia)

    cube root formula part1/3

    cube root formula part2/3

    cube root formula part3/3

    There are 1 to 3 real roots of a general cubic polynomial. The formula above can generate all roots (real and complex) if you multiply C by the cube roots of unity 1, (sqrt(-3) – 1)/2, (-sqrt(-3) – 1)/2. Mysql doesn’t support complex numbers so you’ll have to expand it all out. I concur with gitg0 that this isn’t a very practical way to approach this problem, but it looks doable with some work.

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