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DifferentialGeometry

 RemoveFrame
 remove a frame from a Maple session

 Calling Sequence RemoveFrame(M)

Parameters

 M - an unassigned Maple name or a string

Description

 • Remove a previously defined frame M from the current Maple session.  All protected variables and frame and coframe labels associated with the frame M become unassigned and unprotected.  The command returns the number of frames that remain available.
 • If the current frame is M and M is removed, then the current frame defaults to the first frame in an alphabetic listing of all remaining defined frames.
 • This command is part of the DifferentialGeometry package, and so can be used in the form RemoveFrame(...) only after executing the command with(DifferentialGeometry).  It can always be used in the long form DifferentialGeometry:-RemoveFrame.

Examples

 > $\mathrm{with}\left(\mathrm{DifferentialGeometry}\right):$

Example 1.

Create a pair of manifolds.

 > $\mathrm{DGsetup}\left(\left[x,y\right],M,\mathrm{verbose}\right):$
 ${\mathrm{The following coordinates have been protected:}}$
 $\left[{x}{,}{y}\right]$
 ${\mathrm{The following vector fields have been defined and protected:}}$
 $\left[{\mathrm{_DG}}{}\left(\left[\left[{"vector"}{,}{M}{,}\left[{}\right]\right]{,}\left[\left[\left[{1}\right]{,}{1}\right]\right]\right]\right){,}{\mathrm{_DG}}{}\left(\left[\left[{"vector"}{,}{M}{,}\left[{}\right]\right]{,}\left[\left[\left[{2}\right]{,}{1}\right]\right]\right]\right)\right]$
 ${\mathrm{The following differential 1-forms have been defined and protected:}}$
 $\left[{\mathrm{_DG}}{}\left(\left[\left[{"form"}{,}{M}{,}{1}\right]{,}\left[\left[\left[{1}\right]{,}{1}\right]\right]\right]\right){,}{\mathrm{_DG}}{}\left(\left[\left[{"form"}{,}{M}{,}{1}\right]{,}\left[\left[\left[{2}\right]{,}{1}\right]\right]\right]\right)\right]$ (1)
 > $\mathrm{DGsetup}\left(\left[u,v\right],N,\mathrm{verbose}\right)$
 ${\mathrm{The following coordinates have been protected:}}$
 $\left[{u}{,}{v}\right]$
 ${\mathrm{The following vector fields have been defined and protected:}}$
 $\left[{\mathrm{_DG}}{}\left(\left[\left[{"vector"}{,}{N}{,}\left[{}\right]\right]{,}\left[\left[\left[{1}\right]{,}{1}\right]\right]\right]\right){,}{\mathrm{_DG}}{}\left(\left[\left[{"vector"}{,}{N}{,}\left[{}\right]\right]{,}\left[\left[\left[{2}\right]{,}{1}\right]\right]\right]\right)\right]$
 ${\mathrm{The following differential 1-forms have been defined and protected:}}$
 $\left[{\mathrm{_DG}}{}\left(\left[\left[{"form"}{,}{N}{,}{1}\right]{,}\left[\left[\left[{1}\right]{,}{1}\right]\right]\right]\right){,}{\mathrm{_DG}}{}\left(\left[\left[{"form"}{,}{N}{,}{1}\right]{,}\left[\left[\left[{2}\right]{,}{1}\right]\right]\right]\right)\right]$
 ${\mathrm{frame name: N}}$ (2)

The command DGinfo can return a list of all defined manifolds, adapted frames, Lie algebras, etc. - everything created by DGsetup.

 > $\mathrm{Tools}:-\mathrm{DGinfo}\left("FrameNames"\right)$
 $\left[{M}{,}{N}\right]$ (3)

Note that u is protected and D_u is assigned.

 > $\mathrm{type}\left(u,\mathrm{protected}\right)$
 ${\mathrm{true}}$ (4)
 > $\mathrm{lprint}\left(\mathrm{D_u}\right)$
 _DG([["vector", N, []], [[, 1]]])

Now remove the frame N.

 > $\mathrm{RemoveFrame}\left(N\right)$
 ${1}$ (5)

The frame N no longer shows up in the list of defined frames.

 > $\mathrm{Tools}:-\mathrm{DGinfo}\left("FrameNames"\right)$
 $\left[{M}\right]$ (6)

The current frame is now M.

 > $\mathrm{Tools}:-\mathrm{DGinfo}\left("CurrentFrame"\right)$
 ${M}$ (7)

Also, u is no longer protected and D_u is unassigned.

 > $\mathrm{type}\left(u,\mathrm{protected}\right)$
 ${\mathrm{false}}$ (8)
 > $\mathrm{lprint}\left(\mathrm{D_u}\right)$
 D_u
 M >