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Revision difference : Hamiltonian vector field
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Let $(M,\omega)$ be a symplectic manifold, and $\tom:TM\to T^*M$ be the isomorphism from the tangent Let $(M,\omega)$ be a symplectic manifold, and $\tom:TM\to T^*M$ be the isomorphism from the tangent
bundle to the cotangent bundle $$X\mapsto\om(\cdot,X)$$ and let $f:M\to\R$ is a smooth function. bundle to the cotangent bundle $$X\mapsto\om(\cdot,X)$$ and let $f:M\to\R$ is a smooth function.
Then $H_f=\tom^{-1}(df)$ Then $H_f=\tom^{-1}(df)$
is the {\em Hamiltonian vector field} of $f$. The vector field $H_f$ is \PMlinkname{symplectic}{SymplecticVectorField}, is the {\em Hamiltonian vector field} of $f$. The vector field $H_f$ is \PMlinkname{symplectic}{SymplecticVectorField},
and a symplectic vector field $X$ is \PMlinkid{6410}{Hamiltonian} if and only if the 1-form $\tom(X)= and a symplectic vector field $X$ is Hamiltonian if and only if the 1-form $\tom(X)=
\om(\cdot,X)$ is exact. \om(\cdot,X)$ is exact.
If $T^*Q$ is the cotangent bundle of a manifold $Q$, which is naturally identified with the phase If $T^*Q$ is the cotangent bundle of a manifold $Q$, which is naturally identified with the phase
space of one particle on $Q$, and $f$ is the Hamiltonian, then the flow of the Hamiltonian space of one particle on $Q$, and $f$ is the Hamiltonian, then the flow of the Hamiltonian
vector field $H_f$ is the time flow of the physical system. vector field $H_f$ is the time flow of the physical system.