What does “Reflection along the subspace generated by v” means?











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I got a problem which includes "Reflection along the subspace generated by $v$ in $mathbf{R}^{n+1}$". I need some clarification, what does it mean? Does it mean reflection about the hyperplane $v^{bot}$?










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  • I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
    – Gerry Myerson
    Nov 8 at 5:31










  • Anything to say, PSG?
    – Gerry Myerson
    Nov 13 at 10:19










  • Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
    – PSG
    Nov 13 at 10:34










  • Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
    – Gerry Myerson
    Nov 13 at 11:21






  • 1




    I have written it down.
    – PSG
    9 hours ago















up vote
0
down vote

favorite












I got a problem which includes "Reflection along the subspace generated by $v$ in $mathbf{R}^{n+1}$". I need some clarification, what does it mean? Does it mean reflection about the hyperplane $v^{bot}$?










share|cite|improve this question






















  • I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
    – Gerry Myerson
    Nov 8 at 5:31










  • Anything to say, PSG?
    – Gerry Myerson
    Nov 13 at 10:19










  • Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
    – PSG
    Nov 13 at 10:34










  • Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
    – Gerry Myerson
    Nov 13 at 11:21






  • 1




    I have written it down.
    – PSG
    9 hours ago













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I got a problem which includes "Reflection along the subspace generated by $v$ in $mathbf{R}^{n+1}$". I need some clarification, what does it mean? Does it mean reflection about the hyperplane $v^{bot}$?










share|cite|improve this question













I got a problem which includes "Reflection along the subspace generated by $v$ in $mathbf{R}^{n+1}$". I need some clarification, what does it mean? Does it mean reflection about the hyperplane $v^{bot}$?







linear-algebra vectors euclidean-geometry reflection






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asked Nov 8 at 4:19









PSG

1908




1908












  • I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
    – Gerry Myerson
    Nov 8 at 5:31










  • Anything to say, PSG?
    – Gerry Myerson
    Nov 13 at 10:19










  • Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
    – PSG
    Nov 13 at 10:34










  • Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
    – Gerry Myerson
    Nov 13 at 11:21






  • 1




    I have written it down.
    – PSG
    9 hours ago


















  • I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
    – Gerry Myerson
    Nov 8 at 5:31










  • Anything to say, PSG?
    – Gerry Myerson
    Nov 13 at 10:19










  • Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
    – PSG
    Nov 13 at 10:34










  • Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
    – Gerry Myerson
    Nov 13 at 11:21






  • 1




    I have written it down.
    – PSG
    9 hours ago
















I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
– Gerry Myerson
Nov 8 at 5:31




I would interpret it as reflection in the one-dimensional subspace consisting of the scalar multiples of $v$. But first I'd read the rest of whatever the problem says, and see whether I could deduce the meaning from context. And if I couldn't, then I would ask the person who gave me the problem what interpretation she would give.
– Gerry Myerson
Nov 8 at 5:31












Anything to say, PSG?
– Gerry Myerson
Nov 13 at 10:19




Anything to say, PSG?
– Gerry Myerson
Nov 13 at 10:19












Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
– PSG
Nov 13 at 10:34




Well I think it's as you said in the first comment. Reflection in the 1d subspace. To solve the problem I need it continuous, better if we can get a formula
– PSG
Nov 13 at 10:34












Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
– Gerry Myerson
Nov 13 at 11:21




Do you know how to compute the projection of a vector onto the subspace of scalar multiples of $v$?
– Gerry Myerson
Nov 13 at 11:21




1




1




I have written it down.
– PSG
9 hours ago




I have written it down.
– PSG
9 hours ago










1 Answer
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Thanks to Gerry Myerson who guided me to solve this problem. Here is the solution:



let $mathbf{r}$ be the reflection of the original vector $mathbf{x}$, along the subspace generated by $mathbf{v}$. Then both $mathbf{r}$ and $mathbf{x}$ has same projection onto $mathbf{v}$ as reflection along $mathbf{v}$ will keep the projection onto $mathbf{v}$ intact.



So, $mathbf{x}+mathbf{r}= 2 times $ (Projection of $mathbf{x}$ onto the subspace of scalar multiples of $mathbf{v})= {2 x cdot vover |v|^2}vRightarrow mathbf{r}={2 x cdot vover |v|^2}v- mathbf{x}$






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    Thanks to Gerry Myerson who guided me to solve this problem. Here is the solution:



    let $mathbf{r}$ be the reflection of the original vector $mathbf{x}$, along the subspace generated by $mathbf{v}$. Then both $mathbf{r}$ and $mathbf{x}$ has same projection onto $mathbf{v}$ as reflection along $mathbf{v}$ will keep the projection onto $mathbf{v}$ intact.



    So, $mathbf{x}+mathbf{r}= 2 times $ (Projection of $mathbf{x}$ onto the subspace of scalar multiples of $mathbf{v})= {2 x cdot vover |v|^2}vRightarrow mathbf{r}={2 x cdot vover |v|^2}v- mathbf{x}$






    share|cite|improve this answer



























      up vote
      1
      down vote













      Thanks to Gerry Myerson who guided me to solve this problem. Here is the solution:



      let $mathbf{r}$ be the reflection of the original vector $mathbf{x}$, along the subspace generated by $mathbf{v}$. Then both $mathbf{r}$ and $mathbf{x}$ has same projection onto $mathbf{v}$ as reflection along $mathbf{v}$ will keep the projection onto $mathbf{v}$ intact.



      So, $mathbf{x}+mathbf{r}= 2 times $ (Projection of $mathbf{x}$ onto the subspace of scalar multiples of $mathbf{v})= {2 x cdot vover |v|^2}vRightarrow mathbf{r}={2 x cdot vover |v|^2}v- mathbf{x}$






      share|cite|improve this answer

























        up vote
        1
        down vote










        up vote
        1
        down vote









        Thanks to Gerry Myerson who guided me to solve this problem. Here is the solution:



        let $mathbf{r}$ be the reflection of the original vector $mathbf{x}$, along the subspace generated by $mathbf{v}$. Then both $mathbf{r}$ and $mathbf{x}$ has same projection onto $mathbf{v}$ as reflection along $mathbf{v}$ will keep the projection onto $mathbf{v}$ intact.



        So, $mathbf{x}+mathbf{r}= 2 times $ (Projection of $mathbf{x}$ onto the subspace of scalar multiples of $mathbf{v})= {2 x cdot vover |v|^2}vRightarrow mathbf{r}={2 x cdot vover |v|^2}v- mathbf{x}$






        share|cite|improve this answer














        Thanks to Gerry Myerson who guided me to solve this problem. Here is the solution:



        let $mathbf{r}$ be the reflection of the original vector $mathbf{x}$, along the subspace generated by $mathbf{v}$. Then both $mathbf{r}$ and $mathbf{x}$ has same projection onto $mathbf{v}$ as reflection along $mathbf{v}$ will keep the projection onto $mathbf{v}$ intact.



        So, $mathbf{x}+mathbf{r}= 2 times $ (Projection of $mathbf{x}$ onto the subspace of scalar multiples of $mathbf{v})= {2 x cdot vover |v|^2}vRightarrow mathbf{r}={2 x cdot vover |v|^2}v- mathbf{x}$







        share|cite|improve this answer














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        edited 12 hours ago

























        answered 13 hours ago









        PSG

        1908




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