Overview of the LinearFunctionalSystems Package
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Calling Sequence
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LinearFunctionalSystems[command](arguments)
command(arguments)
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Description
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The LinearFunctionalSystems package is useful for solving the following types of problems.
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* Find polynomial solutions of a linear functional system of equations with polynomial coefficients.
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* Find rational solutions of a linear functional system of equations with polynomial coefficients.
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* Find formal power series solutions of a linear functional system of equations with polynomial coefficients.
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* Find the universal denominator of the rational solutions of a linear functional system of equations with polynomial coefficients
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* Transform a matrix recurrence system into an equivalent system with nonsingular leading or trailing matrix.
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For a given linear functional system of equations, the main functionality of this package is to transform the given system into an equivalent system with a nonsingular leading or trailing matrix. The construction of this equivalent system can be solved by using the EG-elimination algorithm by S.A. Abramov.
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Each command in the LinearFunctionalSystems package can be accessed by using either the long form or the short form of the command name in the command calling sequence.
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As the underlying implementation of the LinearFunctionalSystems package is a module, it is also possible to use the form LinearFunctionalSystems:-command to access a command from the package. For more information, see Module Members.
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List of LinearFunctionalSystems Package Commands
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The following is a list of available commands.
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Examples
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| (2) |
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![sys := [(x+3)*(x+6)*(x+1)*(x+5)*x*y1(x+1)-(x-1)*(x+2)*(x+3)*(x+6)*(x+1)*y1(x)-x*(x^6+11*x^5+41*x^4+65*x^3+50*x^2-36)*y2(x)+(6*(x+2))*(x+3)*(x+6)*(x+1)*x*y4(x), (x+6)*(x+2)*y2(x+1)-x^2*y2(x), (x+6)*(x+1)*(x+5)*x*y3(x+1)+(x+6)*(x+1)*(x-1)*y1(x)-x*(x^5+7*x^4+11*x^3+4*x^2-5*x+6)*y2(x)-y3(x)*(x+6)*(x+1)*(x+5)*x+3*(x+6)*(x+1)*x*(x+3)*y4(x), (x+6)*y4(x+1)+x^2*y2(x)-(x+6)*y4(x)]](/support/helpjp/helpview.aspx?si=8730/file00687/math201.png)
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| (3) |
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![[_c[1]/((x-1)*(x+2)*(x+4)*(x+3)), 0, (1/20)*(20*x^5*_c[2]+200*x^4*_c[2]+700*x^3*_c[2]+1000*x^2*_c[2]+480*x*_c[2]+5*x*_c[1]+4*_c[1])/(x*(x+1)*(x+2)*(x+4)*(x+3)), 0]](/support/helpjp/helpview.aspx?si=8730/file00687/math219.png)
| (4) |
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![sol := [x*(40320*_c[1]-(11621/7150)*_c[5])+O(x^2), -362880*_c[2]+362880*x*_c[2]+O(x^2), _c[3]+x*(362880*_c[4]-(92737/42900)*_c[5])+O(x^2), _c[5]+O(x^2)]](/support/helpjp/helpview.aspx?si=8730/file00687/math226.png)
| (5) |
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| (6) |
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![B := Matrix(4, 4, [[(x^2+3*x+1)*(x-1)/((x+2)*(x+5)*x), (26*x^3+29*x^2+8*x-1+x^5+9*x^4)/((x+2)*(x+5)*(x+1)), -x-1, -(x-1)*(x^3+7*x^2+14*x+9)/((x+2)*(x+5))], [(x-1)/((x+1)*(x+5)*x), (x-1)/((x+1)^2*(x+5)), 0, (x-1)/((x+1)*(x+5))], [(x-1)/(x+5), (x-1)*x/((x+1)*(x+5)), -x, -(x^3+3*x^2-5*x-5)/(x+5)], [-(x-1)/(x*(x+5)), -(x-1)/((x+1)*(x+5)), 1, (x-1)*(x+4)/(x+5)]])](/support/helpjp/helpview.aspx?si=8730/file00687/math237.png)
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| (7) |
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![[-(x^6*_c[1]+7*x^5*_c[1]+x^4*_c[2]-109*x^4*_c[1]+353*x^3*_c[1]-3*x^3*_c[2]-19*x^2*_c[2]+2268*x^2*_c[1]+7*x*_c[2]-840*x*_c[1]-6*_c[2]+720*_c[1])/((x^2-1)*(x+3)*(x+4)*x), -4*(-_c[2]+120*_c[1])/((x+4)*(x+2)*x^2), -(-11*_c[2]-7*x*_c[2]+764*x*_c[1]+2*x^2*_c[2]-260*x^2*_c[1]+x^3*_c[2]-105*x^3*_c[1]+8*x^4*_c[1]+1272*_c[1]+x^5*_c[1])/((x+1)*(x+2)*(x+4)*(x+3)), (x^2*_c[1]+6*x*_c[1]+_c[2]-112*_c[1])/((x+4)*(x+2))]](/support/helpjp/helpview.aspx?si=8730/file00687/math251.png)
| (8) |
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![sol := [x*(-5040*_c[1]+(1014645/16)*_c[5]+(935265/4)*_c[6]-_c[4])+O(x^2), (1633536/7)*_c[6]+(408384/7)*_c[5]+40320*_c[2]+x*(-40320*_c[2]-(744003/14)*_c[5]-(1488006/7)*_c[6])+O(x^2), (128835/8)*_c[5]+(450765/2)*_c[6]+40320*_c[3]+2*_c[4]+x*(-(128835/8)*_c[5]-(450765/2)*_c[6]-40320*_c[3]-_c[4])+O(x^2), _c[4]+x*((5985/2)*_c[6]+(6615/8)*_c[5])+O(x^2)]](/support/helpjp/helpview.aspx?si=8730/file00687/math258.png)
| (9) |
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| (10) |
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References
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Abramov, S.A. "EG-Eliminations." Journal of Difference Equations and Applications, Vol. 5. (1999): 393-433.
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