Change of (orthonormal) basis.











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As I see it, the author says that $[Tv]_{e} = A[v]_{e}$ in the last paragraph. How do I see that ?



enter image description here



I think I've jusitied the first entry in $[Tv]_{e} = A[v]_{e}$ as follows



begin{align*}
langle text{T}v,e_{1}rangle &= langle text{T}e_{1},e_{1}ranglelangle v,e_{1}rangle + cdots + langle text{T}e_{n},e_{1}ranglelangle v,e_{n}rangle\
&=langlelangle text{T}e_{1},e_{1}rangle v,e_{1}ranglerangle\
&=langle text{T}v,e_{1}rangle.
end{align*}



Is there any other way to see it, or interpret it ?










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    up vote
    0
    down vote

    favorite
    1












    As I see it, the author says that $[Tv]_{e} = A[v]_{e}$ in the last paragraph. How do I see that ?



    enter image description here



    I think I've jusitied the first entry in $[Tv]_{e} = A[v]_{e}$ as follows



    begin{align*}
    langle text{T}v,e_{1}rangle &= langle text{T}e_{1},e_{1}ranglelangle v,e_{1}rangle + cdots + langle text{T}e_{n},e_{1}ranglelangle v,e_{n}rangle\
    &=langlelangle text{T}e_{1},e_{1}rangle v,e_{1}ranglerangle\
    &=langle text{T}v,e_{1}rangle.
    end{align*}



    Is there any other way to see it, or interpret it ?










    share|cite|improve this question


























      up vote
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      down vote

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      1









      up vote
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      down vote

      favorite
      1






      1





      As I see it, the author says that $[Tv]_{e} = A[v]_{e}$ in the last paragraph. How do I see that ?



      enter image description here



      I think I've jusitied the first entry in $[Tv]_{e} = A[v]_{e}$ as follows



      begin{align*}
      langle text{T}v,e_{1}rangle &= langle text{T}e_{1},e_{1}ranglelangle v,e_{1}rangle + cdots + langle text{T}e_{n},e_{1}ranglelangle v,e_{n}rangle\
      &=langlelangle text{T}e_{1},e_{1}rangle v,e_{1}ranglerangle\
      &=langle text{T}v,e_{1}rangle.
      end{align*}



      Is there any other way to see it, or interpret it ?










      share|cite|improve this question















      As I see it, the author says that $[Tv]_{e} = A[v]_{e}$ in the last paragraph. How do I see that ?



      enter image description here



      I think I've jusitied the first entry in $[Tv]_{e} = A[v]_{e}$ as follows



      begin{align*}
      langle text{T}v,e_{1}rangle &= langle text{T}e_{1},e_{1}ranglelangle v,e_{1}rangle + cdots + langle text{T}e_{n},e_{1}ranglelangle v,e_{n}rangle\
      &=langlelangle text{T}e_{1},e_{1}rangle v,e_{1}ranglerangle\
      &=langle text{T}v,e_{1}rangle.
      end{align*}



      Is there any other way to see it, or interpret it ?







      linear-algebra






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      edited Oct 12 '13 at 13:41

























      asked Oct 12 '13 at 13:07









      New_to_this

      162111




      162111






















          1 Answer
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          The idea is this - there is a correspondence between matrices in $mathbb{F}^{ntimes n}$ and linear operators in $mathcal{L}(V,V)$.



          To every linear operator $Tin mathcal{L}(V,V)$ one can associate a matrix as follows : Pick a basis $mathcal{B} = {e_i}$ of $V$, and consider the matrix $T_{mathcal{B}}$ whose columns are the vectors ${T(e_i)}$.



          Clearly, this depends on the choice of basis, so the question is : if we choose a different basis $mathcal{B}'$, then how are the two matrices $T_{mathcal{B}}$ and $T_{mathcal{B}'}$ related?



          The answer is : There is an invertible matrix $P$ such that
          $$
          T_{mathcal{B}'} = PT_{mathcal{B}}P^{-1}
          $$






          share|cite|improve this answer





















          • Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
            – New_to_this
            Oct 12 '13 at 13:55











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          up vote
          0
          down vote













          The idea is this - there is a correspondence between matrices in $mathbb{F}^{ntimes n}$ and linear operators in $mathcal{L}(V,V)$.



          To every linear operator $Tin mathcal{L}(V,V)$ one can associate a matrix as follows : Pick a basis $mathcal{B} = {e_i}$ of $V$, and consider the matrix $T_{mathcal{B}}$ whose columns are the vectors ${T(e_i)}$.



          Clearly, this depends on the choice of basis, so the question is : if we choose a different basis $mathcal{B}'$, then how are the two matrices $T_{mathcal{B}}$ and $T_{mathcal{B}'}$ related?



          The answer is : There is an invertible matrix $P$ such that
          $$
          T_{mathcal{B}'} = PT_{mathcal{B}}P^{-1}
          $$






          share|cite|improve this answer





















          • Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
            – New_to_this
            Oct 12 '13 at 13:55















          up vote
          0
          down vote













          The idea is this - there is a correspondence between matrices in $mathbb{F}^{ntimes n}$ and linear operators in $mathcal{L}(V,V)$.



          To every linear operator $Tin mathcal{L}(V,V)$ one can associate a matrix as follows : Pick a basis $mathcal{B} = {e_i}$ of $V$, and consider the matrix $T_{mathcal{B}}$ whose columns are the vectors ${T(e_i)}$.



          Clearly, this depends on the choice of basis, so the question is : if we choose a different basis $mathcal{B}'$, then how are the two matrices $T_{mathcal{B}}$ and $T_{mathcal{B}'}$ related?



          The answer is : There is an invertible matrix $P$ such that
          $$
          T_{mathcal{B}'} = PT_{mathcal{B}}P^{-1}
          $$






          share|cite|improve this answer





















          • Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
            – New_to_this
            Oct 12 '13 at 13:55













          up vote
          0
          down vote










          up vote
          0
          down vote









          The idea is this - there is a correspondence between matrices in $mathbb{F}^{ntimes n}$ and linear operators in $mathcal{L}(V,V)$.



          To every linear operator $Tin mathcal{L}(V,V)$ one can associate a matrix as follows : Pick a basis $mathcal{B} = {e_i}$ of $V$, and consider the matrix $T_{mathcal{B}}$ whose columns are the vectors ${T(e_i)}$.



          Clearly, this depends on the choice of basis, so the question is : if we choose a different basis $mathcal{B}'$, then how are the two matrices $T_{mathcal{B}}$ and $T_{mathcal{B}'}$ related?



          The answer is : There is an invertible matrix $P$ such that
          $$
          T_{mathcal{B}'} = PT_{mathcal{B}}P^{-1}
          $$






          share|cite|improve this answer












          The idea is this - there is a correspondence between matrices in $mathbb{F}^{ntimes n}$ and linear operators in $mathcal{L}(V,V)$.



          To every linear operator $Tin mathcal{L}(V,V)$ one can associate a matrix as follows : Pick a basis $mathcal{B} = {e_i}$ of $V$, and consider the matrix $T_{mathcal{B}}$ whose columns are the vectors ${T(e_i)}$.



          Clearly, this depends on the choice of basis, so the question is : if we choose a different basis $mathcal{B}'$, then how are the two matrices $T_{mathcal{B}}$ and $T_{mathcal{B}'}$ related?



          The answer is : There is an invertible matrix $P$ such that
          $$
          T_{mathcal{B}'} = PT_{mathcal{B}}P^{-1}
          $$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Oct 12 '13 at 13:47









          Prahlad Vaidyanathan

          25.9k12151




          25.9k12151












          • Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
            – New_to_this
            Oct 12 '13 at 13:55


















          • Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
            – New_to_this
            Oct 12 '13 at 13:55
















          Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
          – New_to_this
          Oct 12 '13 at 13:55




          Yes I'm familiar with this diagonalization. My first thought was that A actually is the product that you wrote ind the end. I think that the author just make the statement that T$[v]_{e}=$A$[v]_{e}$ without justifying it.
          – New_to_this
          Oct 12 '13 at 13:55


















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