LAVFSolve - Maple Programming Help

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LAVFSolve

find a LAVF object whose solution space is the sum of the solution spaces of given LAVF objects.

 Calling Sequence LAVFSolve( obj, output = out, consts = c)

Parameters

 obj - a LAVF object that is of finite type (see IsFiniteType) out - (optional) a string: either "solution", "basis", or "lavf" c - (optional) a name or a list of names

Description

 • The LAVFSolve method attempts to solve the determining system in a LAVF object.
 • If solving is successful then by default the method returns a list of solution vector fields.
 • The returned output can be as a basis (by specifying output = "basis") or a new LAVF object (by specifying output = "lavf").
 • For a returned output that involves constants of integration variables, by default these variables are labeled as  _C1, _C2, ...
 • The constant of integration variables can be renamed by specifying the optional argument consts = c.
 – By specifying consts = alpha (i.e. a name), the constants of integration will be named as ${\mathrm{\alpha }}_{1},{\mathrm{\alpha }}_{2},{\mathrm{\alpha }}_{3},..$
 – By specifying consts = [alpha, beta, phi...] (i.e. a list of names), the constants of integration will be named as $\mathrm{\alpha },\mathrm{\beta },\mathrm{\phi },\dots$
 • This is a front-end to the LHSolve method for solving the determining system. LHSolve is associated with the LHPDE object, see Overview of the LHPDE object for more detail.
 • The method throws an exception if the LAVF is not of finite type.
 • This method is associated with the LAVF object. For more detail, see Overview of the LAVF object.

Examples

 > with(LieAlgebrasOfVectorFields):
 > Typesetting:-Settings(userep=true):
 > Typesetting:-Suppress([xi(x,y),eta(x,y)]):
 > V := VectorField(xi(x,y)*D[x] + eta(x,y)*D[y], space = [x,y]);
 ${V}{≔}{\mathrm{\xi }}{}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}{\mathrm{\eta }}{}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}$ (1)
 > E2 := LHPDE([diff(xi(x,y),y,y)=0, diff(eta(x,y),x)=-diff(xi(x,y),y), diff(eta(x,y),y)=0, diff(xi(x,y),x)=0], indep = [x,y], dep = [xi, eta]);
 ${\mathrm{E2}}{≔}\left[{{\mathrm{\xi }}}_{{y}{,}{y}}{=}{0}{,}{{\mathrm{\eta }}}_{{x}}{=}{-}{{\mathrm{\xi }}}_{{y}}{,}{{\mathrm{\eta }}}_{{y}}{=}{0}{,}{{\mathrm{\xi }}}_{{x}}{=}{0}\right]{,}{\mathrm{indep}}{=}\left[{x}{,}{y}\right]{,}{\mathrm{dep}}{=}\left[{\mathrm{\xi }}{,}{\mathrm{\eta }}\right]$ (2)

Construct a vector fields system for E(2).

 > L := LAVF(V, E2);
 ${L}{≔}\left[{\mathrm{\xi }}{}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}{\mathrm{\eta }}{}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}\right]\phantom{\rule[-0.0ex]{0.3em}{0.0ex}}{&where}\phantom{\rule[-0.0ex]{0.3em}{0.0ex}}\left\{\left[{{\mathrm{\xi }}}_{{y}{,}{y}}{=}{0}{,}{{\mathrm{\xi }}}_{{x}}{=}{0}{,}{{\mathrm{\eta }}}_{{x}}{=}{-}{{\mathrm{\xi }}}_{{y}}{,}{{\mathrm{\eta }}}_{{y}}{=}{0}\right]\right\}$ (3)
 > LAVFSolve(L);
 $\left({-}{\mathrm{_C1}}{}{y}{+}{\mathrm{_C3}}\right){}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}\left({\mathrm{_C1}}{}{x}{+}{\mathrm{_C2}}\right){}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}$ (4)
 > LAVFSolve(L, consts = [alpha, beta, delta]);
 $\left({-}{\mathrm{\alpha }}{}{y}{+}{\mathrm{\delta }}\right){}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}\left({\mathrm{\alpha }}{}{x}{+}{\mathrm{\beta }}\right){}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}$ (5)
 > LAVFSolve(L, output = "basis");
 $\left[{-}{y}{}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}{x}{}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{,}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{,}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}\right]$ (6)
 > LAVFSolve(L, output = "lavf", consts = alpha);
 $\left[{\mathrm{\xi }}{}\frac{{\partial }}{{\partial }{x}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}{+}{\mathrm{\eta }}{}\frac{{\partial }}{{\partial }{y}}\phantom{\rule[-0.0ex]{0.4em}{0.0ex}}\right]\phantom{\rule[-0.0ex]{0.3em}{0.0ex}}{&where}\phantom{\rule[-0.0ex]{0.3em}{0.0ex}}\left\{\left[{\mathrm{\xi }}{=}{-}{y}{}{{\mathrm{\alpha }}}_{{1}}{+}{{\mathrm{\alpha }}}_{{3}}{,}{\mathrm{\eta }}{=}{x}{}{{\mathrm{\alpha }}}_{{1}}{+}{{\mathrm{\alpha }}}_{{2}}\right]\right\}$ (7)

Compatibility

 • The LAVFSolve command was introduced in Maple 2020.