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TrySplitOverWrittenFactors​(AngouriMath.​Entity,​AngouriMath.​Entity,​AngouriMath.​Entity.​Variable,​AngouriMath.​Entity@)

 Method (no overloads)

Summary

N/D written as one fraction per factor of denominator,
where the denominator is written as a product of distinct linear and quadratic
factors whose coefficients may be symbols, or false where it is not
or the decomposition cannot be settled.

Remarks

The two splits above work in exact rational arithmetic and stop where the rationals
do, and a symbol is not a rational: 1/((x + a)(x^2 + b)) has factors already in
hand and each of them is a shape the integrator reads, and it was declined because
nothing here could read the factors. This is the textbook method for it -- undetermined
coefficients -- and it is the one that survives a symbol, because it solves a linear
system in the unknown numerators rather than dividing polynomials whose coefficients
have to be compared to zero.
Which pivots are safe. The system's entries are polynomials in the parameters,
and a row reduction has to decide whether a pivot is zero. A number is decided by
looking; a symbolic pivot is taken only when it does not simplify to zero, which is a
judgement and not a proof, and that is why the decomposition is checked before it
is returned
: the identity N = sum P_i * D/F_i is evaluated at several
points with every symbol pinned, and a split that fails it is declined rather than
handed on. A wrong pivot can cost an answer here and cannot produce a wrong one.
The generic case, as everywhere in this integrator: two factors that coincide for
one value of a parameter are coprime for every other, and the answer is the one for
those. See the note on PolynomialLongDivision.
Distinct factors, where a repeated linear one counts as a single block over its whole
power. A repeated symbolic quadratic has no rule to land on and is declined.
https://github.com/asc-community/AngouriMath/issues/718

























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