Is there anything special with a 3x3 matrix where the 3rd row is 0 0 1?












1












$begingroup$


I'm coding using p5.js and I'm looking at this method https://p5js.org/reference/#/p5/applyMatrix



Using that method, I can multiply my current matrix with any matrix of the form:



$$
begin{pmatrix}
a & c & e \
b & d & f \
0 & 0 & 1 \
end{pmatrix}
$$



by calling applyMatrix(a, b, c, d, e, f)



There is no method for multiplying any arbitrary matrix like:
$$
begin{pmatrix}
1 & 2 & 3 \
4 & 5 & 6 \
7 & 8 & 9 \
end{pmatrix}
$$



Is there anything special with a matrix of that form? Is it possible to convert any arbitrary matrix (like the bottom matrix) into a matrix of that form?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Do you have a question about math?
    $endgroup$
    – John Douma
    Jan 18 at 3:34










  • $begingroup$
    My question is about matrices not the coding itself, I just put the link there for context.
    $endgroup$
    – DarkPotatoKing
    Jan 18 at 3:39










  • $begingroup$
    Your question appears to be about some programming language.
    $endgroup$
    – John Douma
    Jan 18 at 3:39










  • $begingroup$
    You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
    $endgroup$
    – Omnomnomnom
    Jan 18 at 3:42






  • 1




    $begingroup$
    @DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
    $endgroup$
    – Alex Provost
    Jan 18 at 3:45
















1












$begingroup$


I'm coding using p5.js and I'm looking at this method https://p5js.org/reference/#/p5/applyMatrix



Using that method, I can multiply my current matrix with any matrix of the form:



$$
begin{pmatrix}
a & c & e \
b & d & f \
0 & 0 & 1 \
end{pmatrix}
$$



by calling applyMatrix(a, b, c, d, e, f)



There is no method for multiplying any arbitrary matrix like:
$$
begin{pmatrix}
1 & 2 & 3 \
4 & 5 & 6 \
7 & 8 & 9 \
end{pmatrix}
$$



Is there anything special with a matrix of that form? Is it possible to convert any arbitrary matrix (like the bottom matrix) into a matrix of that form?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Do you have a question about math?
    $endgroup$
    – John Douma
    Jan 18 at 3:34










  • $begingroup$
    My question is about matrices not the coding itself, I just put the link there for context.
    $endgroup$
    – DarkPotatoKing
    Jan 18 at 3:39










  • $begingroup$
    Your question appears to be about some programming language.
    $endgroup$
    – John Douma
    Jan 18 at 3:39










  • $begingroup$
    You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
    $endgroup$
    – Omnomnomnom
    Jan 18 at 3:42






  • 1




    $begingroup$
    @DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
    $endgroup$
    – Alex Provost
    Jan 18 at 3:45














1












1








1





$begingroup$


I'm coding using p5.js and I'm looking at this method https://p5js.org/reference/#/p5/applyMatrix



Using that method, I can multiply my current matrix with any matrix of the form:



$$
begin{pmatrix}
a & c & e \
b & d & f \
0 & 0 & 1 \
end{pmatrix}
$$



by calling applyMatrix(a, b, c, d, e, f)



There is no method for multiplying any arbitrary matrix like:
$$
begin{pmatrix}
1 & 2 & 3 \
4 & 5 & 6 \
7 & 8 & 9 \
end{pmatrix}
$$



Is there anything special with a matrix of that form? Is it possible to convert any arbitrary matrix (like the bottom matrix) into a matrix of that form?










share|cite|improve this question











$endgroup$




I'm coding using p5.js and I'm looking at this method https://p5js.org/reference/#/p5/applyMatrix



Using that method, I can multiply my current matrix with any matrix of the form:



$$
begin{pmatrix}
a & c & e \
b & d & f \
0 & 0 & 1 \
end{pmatrix}
$$



by calling applyMatrix(a, b, c, d, e, f)



There is no method for multiplying any arbitrary matrix like:
$$
begin{pmatrix}
1 & 2 & 3 \
4 & 5 & 6 \
7 & 8 & 9 \
end{pmatrix}
$$



Is there anything special with a matrix of that form? Is it possible to convert any arbitrary matrix (like the bottom matrix) into a matrix of that form?







matrices






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 18 at 3:46









Alex Provost

15.4k22350




15.4k22350










asked Jan 18 at 3:31









DarkPotatoKingDarkPotatoKing

184




184












  • $begingroup$
    Do you have a question about math?
    $endgroup$
    – John Douma
    Jan 18 at 3:34










  • $begingroup$
    My question is about matrices not the coding itself, I just put the link there for context.
    $endgroup$
    – DarkPotatoKing
    Jan 18 at 3:39










  • $begingroup$
    Your question appears to be about some programming language.
    $endgroup$
    – John Douma
    Jan 18 at 3:39










  • $begingroup$
    You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
    $endgroup$
    – Omnomnomnom
    Jan 18 at 3:42






  • 1




    $begingroup$
    @DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
    $endgroup$
    – Alex Provost
    Jan 18 at 3:45


















  • $begingroup$
    Do you have a question about math?
    $endgroup$
    – John Douma
    Jan 18 at 3:34










  • $begingroup$
    My question is about matrices not the coding itself, I just put the link there for context.
    $endgroup$
    – DarkPotatoKing
    Jan 18 at 3:39










  • $begingroup$
    Your question appears to be about some programming language.
    $endgroup$
    – John Douma
    Jan 18 at 3:39










  • $begingroup$
    You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
    $endgroup$
    – Omnomnomnom
    Jan 18 at 3:42






  • 1




    $begingroup$
    @DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
    $endgroup$
    – Alex Provost
    Jan 18 at 3:45
















$begingroup$
Do you have a question about math?
$endgroup$
– John Douma
Jan 18 at 3:34




$begingroup$
Do you have a question about math?
$endgroup$
– John Douma
Jan 18 at 3:34












$begingroup$
My question is about matrices not the coding itself, I just put the link there for context.
$endgroup$
– DarkPotatoKing
Jan 18 at 3:39




$begingroup$
My question is about matrices not the coding itself, I just put the link there for context.
$endgroup$
– DarkPotatoKing
Jan 18 at 3:39












$begingroup$
Your question appears to be about some programming language.
$endgroup$
– John Douma
Jan 18 at 3:39




$begingroup$
Your question appears to be about some programming language.
$endgroup$
– John Douma
Jan 18 at 3:39












$begingroup$
You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
$endgroup$
– Omnomnomnom
Jan 18 at 3:42




$begingroup$
You could fit your $3 times 3$ matrix into the larger matrix $$ pmatrix{1&2&3&0\4&5&6&0\7&8&9&0\0&0&0&1} $$ which I would say is a "matrix of that form"
$endgroup$
– Omnomnomnom
Jan 18 at 3:42




1




1




$begingroup$
@DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
$endgroup$
– Alex Provost
Jan 18 at 3:45




$begingroup$
@DarkPotatoKing It is used to represent affine transformations. (This is also hinted at in the page you linked.)
$endgroup$
– Alex Provost
Jan 18 at 3:45










1 Answer
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$begingroup$

It is a standard way to represent an affine transformation of the plane; this is how it is used on the page you linked. The submatrix $A = begin{pmatrix} a & c \ b & d end{pmatrix}$ in your question represents the linear part of the affine transformation, and the extra column $t = begin{pmatrix} e \ f end{pmatrix}$ to the right corresponds to the translation part of the transformation. In full, the corresponding transformation maps a vector $v$ to the vector $Av + t$.






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    $begingroup$

    It is a standard way to represent an affine transformation of the plane; this is how it is used on the page you linked. The submatrix $A = begin{pmatrix} a & c \ b & d end{pmatrix}$ in your question represents the linear part of the affine transformation, and the extra column $t = begin{pmatrix} e \ f end{pmatrix}$ to the right corresponds to the translation part of the transformation. In full, the corresponding transformation maps a vector $v$ to the vector $Av + t$.






    share|cite|improve this answer











    $endgroup$


















      5












      $begingroup$

      It is a standard way to represent an affine transformation of the plane; this is how it is used on the page you linked. The submatrix $A = begin{pmatrix} a & c \ b & d end{pmatrix}$ in your question represents the linear part of the affine transformation, and the extra column $t = begin{pmatrix} e \ f end{pmatrix}$ to the right corresponds to the translation part of the transformation. In full, the corresponding transformation maps a vector $v$ to the vector $Av + t$.






      share|cite|improve this answer











      $endgroup$
















        5












        5








        5





        $begingroup$

        It is a standard way to represent an affine transformation of the plane; this is how it is used on the page you linked. The submatrix $A = begin{pmatrix} a & c \ b & d end{pmatrix}$ in your question represents the linear part of the affine transformation, and the extra column $t = begin{pmatrix} e \ f end{pmatrix}$ to the right corresponds to the translation part of the transformation. In full, the corresponding transformation maps a vector $v$ to the vector $Av + t$.






        share|cite|improve this answer











        $endgroup$



        It is a standard way to represent an affine transformation of the plane; this is how it is used on the page you linked. The submatrix $A = begin{pmatrix} a & c \ b & d end{pmatrix}$ in your question represents the linear part of the affine transformation, and the extra column $t = begin{pmatrix} e \ f end{pmatrix}$ to the right corresponds to the translation part of the transformation. In full, the corresponding transformation maps a vector $v$ to the vector $Av + t$.







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited Jan 18 at 3:45

























        answered Jan 18 at 3:37









        Alex ProvostAlex Provost

        15.4k22350




        15.4k22350






























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