What does this absolute value notation mean?












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In a regression model function, What does this absolute value notation mean?



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  • 3




    $begingroup$
    For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
    $endgroup$
    – D.B.
    Jan 14 at 21:27








  • 1




    $begingroup$
    $||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
    $endgroup$
    – lightxbulb
    Jan 14 at 21:27








  • 1




    $begingroup$
    Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
    $endgroup$
    – JMoravitz
    Jan 14 at 21:31












  • $begingroup$
    @D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
    $endgroup$
    – Ibrahim Abouhashish
    Jan 15 at 19:44












  • $begingroup$
    I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
    $endgroup$
    – D.B.
    Jan 17 at 5:30
















0












$begingroup$


In a regression model function, What does this absolute value notation mean?



enter image description here










share|cite|improve this question









$endgroup$








  • 3




    $begingroup$
    For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
    $endgroup$
    – D.B.
    Jan 14 at 21:27








  • 1




    $begingroup$
    $||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
    $endgroup$
    – lightxbulb
    Jan 14 at 21:27








  • 1




    $begingroup$
    Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
    $endgroup$
    – JMoravitz
    Jan 14 at 21:31












  • $begingroup$
    @D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
    $endgroup$
    – Ibrahim Abouhashish
    Jan 15 at 19:44












  • $begingroup$
    I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
    $endgroup$
    – D.B.
    Jan 17 at 5:30














0












0








0





$begingroup$


In a regression model function, What does this absolute value notation mean?



enter image description here










share|cite|improve this question









$endgroup$




In a regression model function, What does this absolute value notation mean?



enter image description here







linear-regression






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asked Jan 14 at 21:24









Ibrahim AbouhashishIbrahim Abouhashish

367




367








  • 3




    $begingroup$
    For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
    $endgroup$
    – D.B.
    Jan 14 at 21:27








  • 1




    $begingroup$
    $||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
    $endgroup$
    – lightxbulb
    Jan 14 at 21:27








  • 1




    $begingroup$
    Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
    $endgroup$
    – JMoravitz
    Jan 14 at 21:31












  • $begingroup$
    @D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
    $endgroup$
    – Ibrahim Abouhashish
    Jan 15 at 19:44












  • $begingroup$
    I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
    $endgroup$
    – D.B.
    Jan 17 at 5:30














  • 3




    $begingroup$
    For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
    $endgroup$
    – D.B.
    Jan 14 at 21:27








  • 1




    $begingroup$
    $||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
    $endgroup$
    – lightxbulb
    Jan 14 at 21:27








  • 1




    $begingroup$
    Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
    $endgroup$
    – JMoravitz
    Jan 14 at 21:31












  • $begingroup$
    @D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
    $endgroup$
    – Ibrahim Abouhashish
    Jan 15 at 19:44












  • $begingroup$
    I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
    $endgroup$
    – D.B.
    Jan 17 at 5:30








3




3




$begingroup$
For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
$endgroup$
– D.B.
Jan 14 at 21:27






$begingroup$
For $n$-dimensional vectors $||cdot||_2$ typically represents the Euclidean, or standard, norm. $||v||_2 = sqrt{v_1^2+v_2^2+...+v_n^2}.$
$endgroup$
– D.B.
Jan 14 at 21:27






1




1




$begingroup$
$||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
$endgroup$
– lightxbulb
Jan 14 at 21:27






$begingroup$
$||x||_2 = sqrt{sum_{i=1}^{n}{x_i^2}}$
$endgroup$
– lightxbulb
Jan 14 at 21:27






1




1




$begingroup$
Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
$endgroup$
– JMoravitz
Jan 14 at 21:31






$begingroup$
Even more generally, $|x|_p = left(sum_{i=1}^n |x_i|^pright)^{1/p}$ is the $p$-norm for $ell_p$ space which Euclidean norm/space is an example of. In your specific example, the super-script $2$ is there as a power so $|x|_2^2 = x_1^2+x_2^2+dots+x_n^2$
$endgroup$
– JMoravitz
Jan 14 at 21:31














$begingroup$
@D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
$endgroup$
– Ibrahim Abouhashish
Jan 15 at 19:44






$begingroup$
@D.B. considering x is also a matrix, what would $ x^{(n)} $ mean
$endgroup$
– Ibrahim Abouhashish
Jan 15 at 19:44














$begingroup$
I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
$endgroup$
– D.B.
Jan 17 at 5:30




$begingroup$
I actually think that $x^{(n)}$ and $y^{(n)}$ are just vectors. The quantity you have shown looks like a measure of the error between your data $y^{(n)}$ and your regression model.
$endgroup$
– D.B.
Jan 17 at 5:30










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