$int_0^t e^{sA}cos(omega s)ds$ with $A$ matrix












1












$begingroup$


Let $A$ be a singular square matrix and $omega,tinmathbb{R}^{*+}$. How to compute the following integral?



$$I = int_0^t e^{sA}cos(omega s),mathrm{d}s$$



Since I am looking for a numerical solutions, I am open to approximations. For example,
$$ I = sum_{k=0}^infty int_0^t dfrac{(sA)^k}{k!} cos(omega s),mathrm{d}s = sum_{k=0}^infty dfrac{A^k}{k!}int_0^t s^k cos(omega s),mathrm{d}s$$



so I can truncate the above sum but I'm wondering if there is a more ingenious approach.










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$endgroup$












  • $begingroup$
    Complex-exponential form of $cos$?..
    $endgroup$
    – metamorphy
    Jan 30 at 10:49










  • $begingroup$
    @metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
    $endgroup$
    – anderstood
    Jan 30 at 10:55






  • 1




    $begingroup$
    Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
    $endgroup$
    – metamorphy
    Jan 30 at 11:02
















1












$begingroup$


Let $A$ be a singular square matrix and $omega,tinmathbb{R}^{*+}$. How to compute the following integral?



$$I = int_0^t e^{sA}cos(omega s),mathrm{d}s$$



Since I am looking for a numerical solutions, I am open to approximations. For example,
$$ I = sum_{k=0}^infty int_0^t dfrac{(sA)^k}{k!} cos(omega s),mathrm{d}s = sum_{k=0}^infty dfrac{A^k}{k!}int_0^t s^k cos(omega s),mathrm{d}s$$



so I can truncate the above sum but I'm wondering if there is a more ingenious approach.










share|cite|improve this question









$endgroup$












  • $begingroup$
    Complex-exponential form of $cos$?..
    $endgroup$
    – metamorphy
    Jan 30 at 10:49










  • $begingroup$
    @metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
    $endgroup$
    – anderstood
    Jan 30 at 10:55






  • 1




    $begingroup$
    Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
    $endgroup$
    – metamorphy
    Jan 30 at 11:02














1












1








1





$begingroup$


Let $A$ be a singular square matrix and $omega,tinmathbb{R}^{*+}$. How to compute the following integral?



$$I = int_0^t e^{sA}cos(omega s),mathrm{d}s$$



Since I am looking for a numerical solutions, I am open to approximations. For example,
$$ I = sum_{k=0}^infty int_0^t dfrac{(sA)^k}{k!} cos(omega s),mathrm{d}s = sum_{k=0}^infty dfrac{A^k}{k!}int_0^t s^k cos(omega s),mathrm{d}s$$



so I can truncate the above sum but I'm wondering if there is a more ingenious approach.










share|cite|improve this question









$endgroup$




Let $A$ be a singular square matrix and $omega,tinmathbb{R}^{*+}$. How to compute the following integral?



$$I = int_0^t e^{sA}cos(omega s),mathrm{d}s$$



Since I am looking for a numerical solutions, I am open to approximations. For example,
$$ I = sum_{k=0}^infty int_0^t dfrac{(sA)^k}{k!} cos(omega s),mathrm{d}s = sum_{k=0}^infty dfrac{A^k}{k!}int_0^t s^k cos(omega s),mathrm{d}s$$



so I can truncate the above sum but I'm wondering if there is a more ingenious approach.







calculus integration matrix-equations matrix-exponential






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share|cite|improve this question











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asked Jan 30 at 10:46









anderstoodanderstood

2,1791030




2,1791030












  • $begingroup$
    Complex-exponential form of $cos$?..
    $endgroup$
    – metamorphy
    Jan 30 at 10:49










  • $begingroup$
    @metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
    $endgroup$
    – anderstood
    Jan 30 at 10:55






  • 1




    $begingroup$
    Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
    $endgroup$
    – metamorphy
    Jan 30 at 11:02


















  • $begingroup$
    Complex-exponential form of $cos$?..
    $endgroup$
    – metamorphy
    Jan 30 at 10:49










  • $begingroup$
    @metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
    $endgroup$
    – anderstood
    Jan 30 at 10:55






  • 1




    $begingroup$
    Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
    $endgroup$
    – metamorphy
    Jan 30 at 11:02
















$begingroup$
Complex-exponential form of $cos$?..
$endgroup$
– metamorphy
Jan 30 at 10:49




$begingroup$
Complex-exponential form of $cos$?..
$endgroup$
– metamorphy
Jan 30 at 10:49












$begingroup$
@metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
$endgroup$
– anderstood
Jan 30 at 10:55




$begingroup$
@metamorphy I thought of it but I am stuck with $e^{sA}e^{iomega s}$ since it does not equal $e^{sA+iomega s}$.
$endgroup$
– anderstood
Jan 30 at 10:55




1




1




$begingroup$
Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
$endgroup$
– metamorphy
Jan 30 at 11:02




$begingroup$
Well, $e^X e^Y=e^{X+Y}$ for commuting matrices $X, Y$. So if your $omega$ is just a scalar, then $e^{sA} e^{iomega s}=e^{s(A+iomega I)}$.
$endgroup$
– metamorphy
Jan 30 at 11:02










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$begingroup$

As suggested by @metamorphy in the comments, it suffices to write



$$ I = operatorname{Re}left(int_0^t e^{s(A+iomega I_n)},mathrm{d}sright)$$
and the computation boils down to the integral of a matrix exponential as addressed in this post.






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    $begingroup$

    As suggested by @metamorphy in the comments, it suffices to write



    $$ I = operatorname{Re}left(int_0^t e^{s(A+iomega I_n)},mathrm{d}sright)$$
    and the computation boils down to the integral of a matrix exponential as addressed in this post.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      As suggested by @metamorphy in the comments, it suffices to write



      $$ I = operatorname{Re}left(int_0^t e^{s(A+iomega I_n)},mathrm{d}sright)$$
      and the computation boils down to the integral of a matrix exponential as addressed in this post.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        As suggested by @metamorphy in the comments, it suffices to write



        $$ I = operatorname{Re}left(int_0^t e^{s(A+iomega I_n)},mathrm{d}sright)$$
        and the computation boils down to the integral of a matrix exponential as addressed in this post.






        share|cite|improve this answer









        $endgroup$



        As suggested by @metamorphy in the comments, it suffices to write



        $$ I = operatorname{Re}left(int_0^t e^{s(A+iomega I_n)},mathrm{d}sright)$$
        and the computation boils down to the integral of a matrix exponential as addressed in this post.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 30 at 13:37









        anderstoodanderstood

        2,1791030




        2,1791030






























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