Combinations of linear mappings












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What I know: the composition of two linear transformations, say $(Mcirc L)(x)$, has the geometric interpretation of successively applying two transformations to $x$, e.g. first a rotation by $L$, then a shear by $M$.



My question is this: What is the geometric interpretation of





  1. $(L+M)(x)$


  2. $(tL)(x)$, where $t$ is some real number?


I would suppose we are simply achieving a new transformation, but I do not know how we this would be different from that defined by $(Mcirc L)(x)$.










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  • $begingroup$
    Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
    $endgroup$
    – Morgan Rodgers
    Jan 24 at 20:40
















0












$begingroup$


What I know: the composition of two linear transformations, say $(Mcirc L)(x)$, has the geometric interpretation of successively applying two transformations to $x$, e.g. first a rotation by $L$, then a shear by $M$.



My question is this: What is the geometric interpretation of





  1. $(L+M)(x)$


  2. $(tL)(x)$, where $t$ is some real number?


I would suppose we are simply achieving a new transformation, but I do not know how we this would be different from that defined by $(Mcirc L)(x)$.










share|cite|improve this question









$endgroup$












  • $begingroup$
    Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
    $endgroup$
    – Morgan Rodgers
    Jan 24 at 20:40














0












0








0





$begingroup$


What I know: the composition of two linear transformations, say $(Mcirc L)(x)$, has the geometric interpretation of successively applying two transformations to $x$, e.g. first a rotation by $L$, then a shear by $M$.



My question is this: What is the geometric interpretation of





  1. $(L+M)(x)$


  2. $(tL)(x)$, where $t$ is some real number?


I would suppose we are simply achieving a new transformation, but I do not know how we this would be different from that defined by $(Mcirc L)(x)$.










share|cite|improve this question









$endgroup$




What I know: the composition of two linear transformations, say $(Mcirc L)(x)$, has the geometric interpretation of successively applying two transformations to $x$, e.g. first a rotation by $L$, then a shear by $M$.



My question is this: What is the geometric interpretation of





  1. $(L+M)(x)$


  2. $(tL)(x)$, where $t$ is some real number?


I would suppose we are simply achieving a new transformation, but I do not know how we this would be different from that defined by $(Mcirc L)(x)$.







linear-algebra






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asked Jan 24 at 20:24









Julia KimJulia Kim

174




174












  • $begingroup$
    Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
    $endgroup$
    – Morgan Rodgers
    Jan 24 at 20:40


















  • $begingroup$
    Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
    $endgroup$
    – Morgan Rodgers
    Jan 24 at 20:40
















$begingroup$
Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
$endgroup$
– Morgan Rodgers
Jan 24 at 20:40




$begingroup$
Well, if you took $frac{1}{2}(L+M)(x)$, the result would be the average of the two transformations.
$endgroup$
– Morgan Rodgers
Jan 24 at 20:40










1 Answer
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$begingroup$

In some sense, 2 is again of the form $(tI_ncirc L)(x)$, and you may regard this as first applying L, followed by the action of the linear map $tI_n$, and $tI_n$ uniformly dilates all vectors by t away from the origin. (order you perform these is immaterial in this case)



For 1, $(L+M)(x)= L(x)+M(x)$ holds, and provided that they have the same domain/codomain, then $L+M$ is just another linear transformation. You can simply think of it as adding the images under M and L together.






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    $begingroup$

    In some sense, 2 is again of the form $(tI_ncirc L)(x)$, and you may regard this as first applying L, followed by the action of the linear map $tI_n$, and $tI_n$ uniformly dilates all vectors by t away from the origin. (order you perform these is immaterial in this case)



    For 1, $(L+M)(x)= L(x)+M(x)$ holds, and provided that they have the same domain/codomain, then $L+M$ is just another linear transformation. You can simply think of it as adding the images under M and L together.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      In some sense, 2 is again of the form $(tI_ncirc L)(x)$, and you may regard this as first applying L, followed by the action of the linear map $tI_n$, and $tI_n$ uniformly dilates all vectors by t away from the origin. (order you perform these is immaterial in this case)



      For 1, $(L+M)(x)= L(x)+M(x)$ holds, and provided that they have the same domain/codomain, then $L+M$ is just another linear transformation. You can simply think of it as adding the images under M and L together.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        In some sense, 2 is again of the form $(tI_ncirc L)(x)$, and you may regard this as first applying L, followed by the action of the linear map $tI_n$, and $tI_n$ uniformly dilates all vectors by t away from the origin. (order you perform these is immaterial in this case)



        For 1, $(L+M)(x)= L(x)+M(x)$ holds, and provided that they have the same domain/codomain, then $L+M$ is just another linear transformation. You can simply think of it as adding the images under M and L together.






        share|cite|improve this answer









        $endgroup$



        In some sense, 2 is again of the form $(tI_ncirc L)(x)$, and you may regard this as first applying L, followed by the action of the linear map $tI_n$, and $tI_n$ uniformly dilates all vectors by t away from the origin. (order you perform these is immaterial in this case)



        For 1, $(L+M)(x)= L(x)+M(x)$ holds, and provided that they have the same domain/codomain, then $L+M$ is just another linear transformation. You can simply think of it as adding the images under M and L together.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 24 at 20:39









        AlexandrosAlexandros

        9421412




        9421412






























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