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Lagrangian-variation-xPert-VarD.nb
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Lagrangian-variation-xPert-VarD.nb
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Cell["Variation of Lagrangian with xPert and VarD", "Subtitle"],
Cell["\<\
Leo C. Stein ([email protected])
August 2013\
\>", "Subsubtitle"],
Cell["\<\
Summary: A common usage pattern for varying a Lagrangian.
VarD doesn\[CloseCurlyQuote]t know more complicated math like the variation \
of a curvature tensor with respect to the metric. However, xPert does, so \
combining them makes it straightforward to vary Lagrangian.\
\>", "Subsubtitle"],
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Here\[CloseCurlyQuote]s the Lagrangian density for GR:\
\>", "Text"],
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First find the linear perturbation, expanding it, then \
contract/canonicalize/simplify.\
\>", "Text"],
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Now perform (minus) the variation with respect to h[LI[1],a,b]. This will \
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