Explanation of some tensors in more detail

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I’m an engineering student and I was taught to use some kind of tensors to describe properties of materials, however, I have been trying to learn more about them in more detail for a couple of days, so excuse me if I’m mathematically wrong with something during the post.



I understand that if we have a multilinear function, we can associate it with a tensor object. If $V$ is a vectorial space, then



$$
f:underbraceV times cdots times V_text$n$ times rightarrow mathbbR quad textassociates with quad T : underbraceV times cdots times V_text$n$ times rightarrow mathbbR
$$



where we say that $T$ is a tensor $n$ times covariant.



With this, we could say for example that the dot product between two vectors is a tensor two times covariant. The problem for my understanding is when considering generic multilinear applications such that



$$
f : underbraceV times cdots times V_text$n$ times rightarrow underbraceV times cdots times V_text$m$ times
$$



Here it’s supposed that we could get a tensor as



$$
T : Vunderbrace^* times cdots times V^*_text$m$ times times underbraceV times cdots times V_text$n$ times rightarrow mathbbR
$$



where $V^*$ is the dual space (let’s say that is the same as $V$ but with row vectors instead of column ones), and then $T$ is said to be $m$ times contravariant and $n$ times covariant, or a tensor of type $(m,n)$.



In this scenario I can see easily that a matrix $A$ that transforms one vector into another, could be seen as a tensor of type $(1,1)$, because



$$
A : V rightarrow V Rightarrow quad textleads to quad T : V^* times V rightarrow mathbbR
$$



So my question is, knowing that column vectors could be seen as tensors of type $(0,1)$ and row vectors as those of type $(1,0)$, how can I achieve this result with a similar way of thinking to the one used for matrix $A$ or the dot product?







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    I’m an engineering student and I was taught to use some kind of tensors to describe properties of materials, however, I have been trying to learn more about them in more detail for a couple of days, so excuse me if I’m mathematically wrong with something during the post.



    I understand that if we have a multilinear function, we can associate it with a tensor object. If $V$ is a vectorial space, then



    $$
    f:underbraceV times cdots times V_text$n$ times rightarrow mathbbR quad textassociates with quad T : underbraceV times cdots times V_text$n$ times rightarrow mathbbR
    $$



    where we say that $T$ is a tensor $n$ times covariant.



    With this, we could say for example that the dot product between two vectors is a tensor two times covariant. The problem for my understanding is when considering generic multilinear applications such that



    $$
    f : underbraceV times cdots times V_text$n$ times rightarrow underbraceV times cdots times V_text$m$ times
    $$



    Here it’s supposed that we could get a tensor as



    $$
    T : Vunderbrace^* times cdots times V^*_text$m$ times times underbraceV times cdots times V_text$n$ times rightarrow mathbbR
    $$



    where $V^*$ is the dual space (let’s say that is the same as $V$ but with row vectors instead of column ones), and then $T$ is said to be $m$ times contravariant and $n$ times covariant, or a tensor of type $(m,n)$.



    In this scenario I can see easily that a matrix $A$ that transforms one vector into another, could be seen as a tensor of type $(1,1)$, because



    $$
    A : V rightarrow V Rightarrow quad textleads to quad T : V^* times V rightarrow mathbbR
    $$



    So my question is, knowing that column vectors could be seen as tensors of type $(0,1)$ and row vectors as those of type $(1,0)$, how can I achieve this result with a similar way of thinking to the one used for matrix $A$ or the dot product?







    share|cite|improve this question























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I’m an engineering student and I was taught to use some kind of tensors to describe properties of materials, however, I have been trying to learn more about them in more detail for a couple of days, so excuse me if I’m mathematically wrong with something during the post.



      I understand that if we have a multilinear function, we can associate it with a tensor object. If $V$ is a vectorial space, then



      $$
      f:underbraceV times cdots times V_text$n$ times rightarrow mathbbR quad textassociates with quad T : underbraceV times cdots times V_text$n$ times rightarrow mathbbR
      $$



      where we say that $T$ is a tensor $n$ times covariant.



      With this, we could say for example that the dot product between two vectors is a tensor two times covariant. The problem for my understanding is when considering generic multilinear applications such that



      $$
      f : underbraceV times cdots times V_text$n$ times rightarrow underbraceV times cdots times V_text$m$ times
      $$



      Here it’s supposed that we could get a tensor as



      $$
      T : Vunderbrace^* times cdots times V^*_text$m$ times times underbraceV times cdots times V_text$n$ times rightarrow mathbbR
      $$



      where $V^*$ is the dual space (let’s say that is the same as $V$ but with row vectors instead of column ones), and then $T$ is said to be $m$ times contravariant and $n$ times covariant, or a tensor of type $(m,n)$.



      In this scenario I can see easily that a matrix $A$ that transforms one vector into another, could be seen as a tensor of type $(1,1)$, because



      $$
      A : V rightarrow V Rightarrow quad textleads to quad T : V^* times V rightarrow mathbbR
      $$



      So my question is, knowing that column vectors could be seen as tensors of type $(0,1)$ and row vectors as those of type $(1,0)$, how can I achieve this result with a similar way of thinking to the one used for matrix $A$ or the dot product?







      share|cite|improve this question













      I’m an engineering student and I was taught to use some kind of tensors to describe properties of materials, however, I have been trying to learn more about them in more detail for a couple of days, so excuse me if I’m mathematically wrong with something during the post.



      I understand that if we have a multilinear function, we can associate it with a tensor object. If $V$ is a vectorial space, then



      $$
      f:underbraceV times cdots times V_text$n$ times rightarrow mathbbR quad textassociates with quad T : underbraceV times cdots times V_text$n$ times rightarrow mathbbR
      $$



      where we say that $T$ is a tensor $n$ times covariant.



      With this, we could say for example that the dot product between two vectors is a tensor two times covariant. The problem for my understanding is when considering generic multilinear applications such that



      $$
      f : underbraceV times cdots times V_text$n$ times rightarrow underbraceV times cdots times V_text$m$ times
      $$



      Here it’s supposed that we could get a tensor as



      $$
      T : Vunderbrace^* times cdots times V^*_text$m$ times times underbraceV times cdots times V_text$n$ times rightarrow mathbbR
      $$



      where $V^*$ is the dual space (let’s say that is the same as $V$ but with row vectors instead of column ones), and then $T$ is said to be $m$ times contravariant and $n$ times covariant, or a tensor of type $(m,n)$.



      In this scenario I can see easily that a matrix $A$ that transforms one vector into another, could be seen as a tensor of type $(1,1)$, because



      $$
      A : V rightarrow V Rightarrow quad textleads to quad T : V^* times V rightarrow mathbbR
      $$



      So my question is, knowing that column vectors could be seen as tensors of type $(0,1)$ and row vectors as those of type $(1,0)$, how can I achieve this result with a similar way of thinking to the one used for matrix $A$ or the dot product?









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      share|cite|improve this question




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      edited Jul 24 at 9:17









      md2perpe

      5,83511022




      5,83511022









      asked Jul 23 at 23:12









      Jaime_mc2

      1017




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