DifferentialGeometry[algebraic operations] - addition, subtraction, scalar multiplication, wedge product, tensor product
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Calling Sequence
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A &plus B - add two vectors, differential forms or tensors
A &minus B- subtract one vector, differential form or tensor from another
A &mult B - multiply a Maple expression by a vector, differential form or tensor
A &wedge B- form the wedge (or skew) product of a pair of differential forms
A &tensor B- form the tensor product of a pair of tensors
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Parameters
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A, B
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Maple expressions, differential forms or tensors
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Description
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In the DifferentialGeometry package the wedge product of 1-forms is defined in terms of the tensor product by
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alpha &wedge beta = alpha &tensor beta - beta &tensor alpha.
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When using these commands together within a single Maple expression, it is important to use parentheses to insure that the operations are executed in the correct order.
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In an interactive Maple session, it is usually more convenient to use the commands evalDG and DGzip to perform these basic algebraic operations.
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Here are the precise lists of admissible arguments for these commands.
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A &plus B, A &minus B -- A and B: Maple expressions, vectors, differential forms of the same degree, differential biforms of the same bidegree, tensors with the same index type and density weights. A and B must be defined on the same frame.
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A &mult B -- A: a Maple expression; B: a Maple expression, vector, differential form, differential biform, tensor. A and B must be defined on the same frame.
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A &wedge B -- A and B: Maple expressions or differential forms, differential biforms. If A and B are forms, then the sum of their degrees cannot exceed the dimension of the frame on which they are defined. If A and B are bi-forms, then the sum of their horizontal degrees cannot exceed the dimension of the base manifold on which they are defined. A and B must be defined on the same frame.
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A &tensor B -- A and B: Maple expressions, vectors, differential 1-forms, tensors. A and B must be defined on the same frame.
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These commands are part of the DifferentialGeometry package, and so can be used in the forms given above only after executing the command with(DifferentialGeometry).
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Examples
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Use DGsetup to define a 3-dimensional manifold M with coordinates [x, y, z].
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Example 1.
Create linear combinations of vector fields and differential 1-forms using &plus and &mult.
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Example 2.
Create differential 2-forms using &plus and &mult and &wedge.
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Example 3.
Create various tensors using &plus, &mult and &tensor.
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