Principle of least action and Euler-Lagrange equation

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Define the action



$S[g]=displaystylefrac12int^1_0 Tr(I(g^-1dot g)~g^-1dot g)~dt.$



$I:SO(N)to SO(N)$ denotes the endomorphism $omega to I(omega)$ with $I(omega)_ij=omega_ij/F_ij$



$g:[0,1]to SO(N)$



How to use the principle of least action or Euler-Lagrange equation to derive something like this (A differential equation with Lie bracket):



$dot A=[A,B],~~dot g =gB,$ where $B_ij=F_ijA_ij$ and $F$ is a symmetric matrix with strictly positive entries. (Actually, this is not the true result.)







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  • Where does this originate from?
    – mvw
    Jul 24 at 20:48










  • @mvw It is from a paper that my professor assign me to read
    – learner
    Jul 24 at 21:07










  • Crossposted from physics.stackexchange.com/q/419302/2451
    – Qmechanic
    Jul 25 at 8:25














up vote
1
down vote

favorite












Define the action



$S[g]=displaystylefrac12int^1_0 Tr(I(g^-1dot g)~g^-1dot g)~dt.$



$I:SO(N)to SO(N)$ denotes the endomorphism $omega to I(omega)$ with $I(omega)_ij=omega_ij/F_ij$



$g:[0,1]to SO(N)$



How to use the principle of least action or Euler-Lagrange equation to derive something like this (A differential equation with Lie bracket):



$dot A=[A,B],~~dot g =gB,$ where $B_ij=F_ijA_ij$ and $F$ is a symmetric matrix with strictly positive entries. (Actually, this is not the true result.)







share|cite|improve this question



















  • Where does this originate from?
    – mvw
    Jul 24 at 20:48










  • @mvw It is from a paper that my professor assign me to read
    – learner
    Jul 24 at 21:07










  • Crossposted from physics.stackexchange.com/q/419302/2451
    – Qmechanic
    Jul 25 at 8:25












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Define the action



$S[g]=displaystylefrac12int^1_0 Tr(I(g^-1dot g)~g^-1dot g)~dt.$



$I:SO(N)to SO(N)$ denotes the endomorphism $omega to I(omega)$ with $I(omega)_ij=omega_ij/F_ij$



$g:[0,1]to SO(N)$



How to use the principle of least action or Euler-Lagrange equation to derive something like this (A differential equation with Lie bracket):



$dot A=[A,B],~~dot g =gB,$ where $B_ij=F_ijA_ij$ and $F$ is a symmetric matrix with strictly positive entries. (Actually, this is not the true result.)







share|cite|improve this question











Define the action



$S[g]=displaystylefrac12int^1_0 Tr(I(g^-1dot g)~g^-1dot g)~dt.$



$I:SO(N)to SO(N)$ denotes the endomorphism $omega to I(omega)$ with $I(omega)_ij=omega_ij/F_ij$



$g:[0,1]to SO(N)$



How to use the principle of least action or Euler-Lagrange equation to derive something like this (A differential equation with Lie bracket):



$dot A=[A,B],~~dot g =gB,$ where $B_ij=F_ijA_ij$ and $F$ is a symmetric matrix with strictly positive entries. (Actually, this is not the true result.)









share|cite|improve this question










share|cite|improve this question




share|cite|improve this question









asked Jul 24 at 20:39









learner

29916




29916











  • Where does this originate from?
    – mvw
    Jul 24 at 20:48










  • @mvw It is from a paper that my professor assign me to read
    – learner
    Jul 24 at 21:07










  • Crossposted from physics.stackexchange.com/q/419302/2451
    – Qmechanic
    Jul 25 at 8:25
















  • Where does this originate from?
    – mvw
    Jul 24 at 20:48










  • @mvw It is from a paper that my professor assign me to read
    – learner
    Jul 24 at 21:07










  • Crossposted from physics.stackexchange.com/q/419302/2451
    – Qmechanic
    Jul 25 at 8:25















Where does this originate from?
– mvw
Jul 24 at 20:48




Where does this originate from?
– mvw
Jul 24 at 20:48












@mvw It is from a paper that my professor assign me to read
– learner
Jul 24 at 21:07




@mvw It is from a paper that my professor assign me to read
– learner
Jul 24 at 21:07












Crossposted from physics.stackexchange.com/q/419302/2451
– Qmechanic
Jul 25 at 8:25




Crossposted from physics.stackexchange.com/q/419302/2451
– Qmechanic
Jul 25 at 8:25















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