Stability of a linear equation












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$begingroup$


If $A$ is a matrix, then $e^{At} leq C e^{-lambda t}$ if and only if the spectrum of $A$ consists of eigenvalues with negative real parts.



Is there a similar result, relating stability to the spectrum, when $A$ is a non-selfadjoint operator, when $e^{-At}$ is interpreted as the solution to
$$frac{partial u}{partial t} = - A u,$$
with appropriate boundary conditions? I assume that there is, but I haven't been able to find a reference.










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$endgroup$

















    0












    $begingroup$


    If $A$ is a matrix, then $e^{At} leq C e^{-lambda t}$ if and only if the spectrum of $A$ consists of eigenvalues with negative real parts.



    Is there a similar result, relating stability to the spectrum, when $A$ is a non-selfadjoint operator, when $e^{-At}$ is interpreted as the solution to
    $$frac{partial u}{partial t} = - A u,$$
    with appropriate boundary conditions? I assume that there is, but I haven't been able to find a reference.










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      If $A$ is a matrix, then $e^{At} leq C e^{-lambda t}$ if and only if the spectrum of $A$ consists of eigenvalues with negative real parts.



      Is there a similar result, relating stability to the spectrum, when $A$ is a non-selfadjoint operator, when $e^{-At}$ is interpreted as the solution to
      $$frac{partial u}{partial t} = - A u,$$
      with appropriate boundary conditions? I assume that there is, but I haven't been able to find a reference.










      share|cite|improve this question









      $endgroup$




      If $A$ is a matrix, then $e^{At} leq C e^{-lambda t}$ if and only if the spectrum of $A$ consists of eigenvalues with negative real parts.



      Is there a similar result, relating stability to the spectrum, when $A$ is a non-selfadjoint operator, when $e^{-At}$ is interpreted as the solution to
      $$frac{partial u}{partial t} = - A u,$$
      with appropriate boundary conditions? I assume that there is, but I haven't been able to find a reference.







      operator-theory stability-theory






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      asked Jan 12 at 18:24









      Roberto RastapopoulosRoberto Rastapopoulos

      896424




      896424






















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          $begingroup$

          You need some assumptions on $A$ to have a unique solution of the evolution equation (and one should also talk about the type of solution). Anyway, I think the answer to your question lies in the Hille-Yosida theorem:



          If $A$ is the generator of the strongly continuous semigroup $T$, then $|T(t)|leq M e^{omega t}$ if and only if the spectrum of $A$ is contained in the half-plane ${zinmathbb{C}mid operatorname{Re}zleq omega}$.



          In this case $u(t)=T(t)x$ is the unique mild solution of the initial value problem
          begin{align*}
          dot u(t)&=Au(t),\
          u(0)&=x.
          end{align*}

          The Hille-Yosida theorem also gives a characterization of the operator that generate strongly continuous semigroups.






          share|cite|improve this answer









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            $begingroup$

            You need some assumptions on $A$ to have a unique solution of the evolution equation (and one should also talk about the type of solution). Anyway, I think the answer to your question lies in the Hille-Yosida theorem:



            If $A$ is the generator of the strongly continuous semigroup $T$, then $|T(t)|leq M e^{omega t}$ if and only if the spectrum of $A$ is contained in the half-plane ${zinmathbb{C}mid operatorname{Re}zleq omega}$.



            In this case $u(t)=T(t)x$ is the unique mild solution of the initial value problem
            begin{align*}
            dot u(t)&=Au(t),\
            u(0)&=x.
            end{align*}

            The Hille-Yosida theorem also gives a characterization of the operator that generate strongly continuous semigroups.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              You need some assumptions on $A$ to have a unique solution of the evolution equation (and one should also talk about the type of solution). Anyway, I think the answer to your question lies in the Hille-Yosida theorem:



              If $A$ is the generator of the strongly continuous semigroup $T$, then $|T(t)|leq M e^{omega t}$ if and only if the spectrum of $A$ is contained in the half-plane ${zinmathbb{C}mid operatorname{Re}zleq omega}$.



              In this case $u(t)=T(t)x$ is the unique mild solution of the initial value problem
              begin{align*}
              dot u(t)&=Au(t),\
              u(0)&=x.
              end{align*}

              The Hille-Yosida theorem also gives a characterization of the operator that generate strongly continuous semigroups.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                You need some assumptions on $A$ to have a unique solution of the evolution equation (and one should also talk about the type of solution). Anyway, I think the answer to your question lies in the Hille-Yosida theorem:



                If $A$ is the generator of the strongly continuous semigroup $T$, then $|T(t)|leq M e^{omega t}$ if and only if the spectrum of $A$ is contained in the half-plane ${zinmathbb{C}mid operatorname{Re}zleq omega}$.



                In this case $u(t)=T(t)x$ is the unique mild solution of the initial value problem
                begin{align*}
                dot u(t)&=Au(t),\
                u(0)&=x.
                end{align*}

                The Hille-Yosida theorem also gives a characterization of the operator that generate strongly continuous semigroups.






                share|cite|improve this answer









                $endgroup$



                You need some assumptions on $A$ to have a unique solution of the evolution equation (and one should also talk about the type of solution). Anyway, I think the answer to your question lies in the Hille-Yosida theorem:



                If $A$ is the generator of the strongly continuous semigroup $T$, then $|T(t)|leq M e^{omega t}$ if and only if the spectrum of $A$ is contained in the half-plane ${zinmathbb{C}mid operatorname{Re}zleq omega}$.



                In this case $u(t)=T(t)x$ is the unique mild solution of the initial value problem
                begin{align*}
                dot u(t)&=Au(t),\
                u(0)&=x.
                end{align*}

                The Hille-Yosida theorem also gives a characterization of the operator that generate strongly continuous semigroups.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 15 at 13:01









                MaoWaoMaoWao

                2,853617




                2,853617






























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