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gibson:teaching:fall-2016:math753:horner [2016/11/11 11:29] gibson created |
gibson:teaching:fall-2016:math753:horner [2016/11/11 11:37] (current) gibson |
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- | ====== Horner's method ====== | + | ====== Horner's method for polynomial evaluation ====== |
===Horner's method without base points === | ===Horner's method without base points === | ||
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\end{equation*} | \end{equation*} | ||
- | evaluation only requires 4 adds and 4 multiplies. The payoff gets bigger for higher-order polynomials. | + | evaluation only requires 4 adds and 4 multiplies. It's easy to see that these are just two different ways of writing the exact same polynomial. The approach generalizes to arbitrary-order polynomials, and the payoff gets bigger as the order of the polynomial increases. |
=== Horner's method with base points === | === Horner's method with base points === | ||
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The above polynomial is still 4th order, and it is clearly possible to write any polynomial in a form like this for arbitrary $b$'s. The base points require an additional set of subtractions, but it's often worth the trouble, primarily because this is the most natural form for polynomial interpolation via [[gibson:teaching:fall-2016:math753:newtondivdiff|Newton's Divided Differences]]. | The above polynomial is still 4th order, and it is clearly possible to write any polynomial in a form like this for arbitrary $b$'s. The base points require an additional set of subtractions, but it's often worth the trouble, primarily because this is the most natural form for polynomial interpolation via [[gibson:teaching:fall-2016:math753:newtondivdiff|Newton's Divided Differences]]. | ||
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+ | Further reading: | ||
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+ | * [[https://en.wikipedia.org/wiki/Horner%27s_method | Horner's method]] (wikipedia). | ||
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+ | Strangely, there aren't many good online resources for Horner's method. Perhaps it's too simple. so | ||