QDifferenceEquations[SeriesSolution] - return a series solution of a q-difference equation
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Calling Sequence
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SeriesSolution(eq, var, inits, output=type, dataname)
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Parameters
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eq
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q-difference equation or a list of such equations (for the system case)
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var
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function variable to solve for, such as , or a list of such function variables (for the system case)
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inits
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set of initial conditions
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output=type
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(optional) where type is one of basis[C] or onesol and "C" is a name. The words output, basis and onesol must be used literally.
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dataname
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(optional) name; if given the name is set to special data needed to extend the series found to higher degree with QDifferenceEquations[ExtendSeries]
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Description
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The SeriesSolution command returns the series solution of the given linear q-difference equation with polynomial coefficients. If such a solution does not exist, then NULL is returned.
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Additionally, if a name given in the dataname parameter, then the command sets the name to special data needed to extend the series found to higher degree with QDifferenceEquations[ExtendSeries] command.
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The SeriesSolution command solves the problem with a single q-difference equation and also with a system of such equations. In the latter case the command invokes LinearFunctionalSystems[SeriesSolution] in order to find solutions.
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The solution is a series expansions in x, corresponding to var. The order term (for example ) is the last term in the series. For the system case the solution is a list of such series expansions.
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For a single q-difference equation the function computes some initial terms of the series. The number of the terms is determined in such a way that the process of computing the successive terms does not lead to new arbitrary constants. The successive terms can be computed with the QDifferenceEquations[ExtendSeries].
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The parameter q in a scalar q-difference equation can be either a name or a rational number.
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Output options
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Optionally, you can specify output=basis, output=basis[var], output=onesol, output=gensol, or output=anysol.
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The output is provided as a single algebraic expression that is a -linear combination of the independent solutions plus any particular solution for the inhomogeneous case. The independent solutions will have indexed coefficients of the form , where var is as provided in the output=basis[C] option.
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This specifies that only a single solution be provided as output.
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The inits argument is in fact ignored and allowed in the calling sequence for compatibility with the other solvers in the package.
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Examples
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