Rational function #335
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Rational function #335
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@@ Coverage Diff @@
## master #335 +/- ##
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- Coverage 91.54% 82.85% -8.70%
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Files 16 21 +5
Lines 1963 2420 +457
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+ Hits 1797 2005 +208
- Misses 166 415 +249
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This adds an
AbstractRationalFunctiontype for holding rational functions. In #308 it was suggested that this could be useful. Construction of the primaryRationalFunctiontype borrows the//syntax from theRationaltype of Base. Other subtypes are possible.The https://github.com/andreasvarga/DescriptorSystems.jl/blob/main/src/types/RationalFunction.jl implementation is mostly realized as a subtype of
AbstractRationalFunctionas an example (for now it isn't included when the package is loaded).The https://github.com/aytekinar/RationalFunctions.jl package was a guide, but the main
RationalFunctionimplementation does not include information about conjugated variables.The
conjmethod has not (yet) been defined.The new exports are
polesandresidues. The "zeros" are found byroots. As well, the functionlowest_termsis exported to cancel common factors. (The namecancelis used in SymPy and Mathematica, but wasn't used for this as it seemed like a useful generic elsewhere, though it is tempting.)There is a simple implementation for fitting rational functions using least squares,
fit(RationalFunction, xs, ys, m, n). (There are more accurate and robust fitting implementations elsewhere in the package ecosystem, such asBaryRational.) As for fitting, this provides a natural home for thePadefunction that is still available viaPolyCompat, and now re-implemented byfit(RationalFunction, p::Polynomial, m,n).The
plotrecipe seems to do an okay job of plotting basic rational functions, though perhaps it could be tweaked in places.