Partial derivative of a function defined in a rectangular area












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I noticed in a book that it considers a function $u(x,y)$ in the rectangular area : $xin (0, 1)$ ,$yin (0, 1]$, and takes there the $partial_y$. As I am used to only to take partial derivatives in open sets, I would appreciate a clarification of the value of $partial_y(x, 1)$. Is it $$partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$ or something else? Thanks in advance.










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    $begingroup$


    I noticed in a book that it considers a function $u(x,y)$ in the rectangular area : $xin (0, 1)$ ,$yin (0, 1]$, and takes there the $partial_y$. As I am used to only to take partial derivatives in open sets, I would appreciate a clarification of the value of $partial_y(x, 1)$. Is it $$partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$ or something else? Thanks in advance.










    share|cite|improve this question











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      0





      $begingroup$


      I noticed in a book that it considers a function $u(x,y)$ in the rectangular area : $xin (0, 1)$ ,$yin (0, 1]$, and takes there the $partial_y$. As I am used to only to take partial derivatives in open sets, I would appreciate a clarification of the value of $partial_y(x, 1)$. Is it $$partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$ or something else? Thanks in advance.










      share|cite|improve this question











      $endgroup$




      I noticed in a book that it considers a function $u(x,y)$ in the rectangular area : $xin (0, 1)$ ,$yin (0, 1]$, and takes there the $partial_y$. As I am used to only to take partial derivatives in open sets, I would appreciate a clarification of the value of $partial_y(x, 1)$. Is it $$partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$ or something else? Thanks in advance.







      calculus multivariable-calculus derivatives






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      edited Jan 4 at 3:59







      dmtri

















      asked Jan 3 at 15:13









      dmtridmtri

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          $begingroup$

          Yes, your definition of partial derivative with respect to $y$ at $(x,1)$



          $$ partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$



          is correct. Of course it is one sided because we do not have $y>1$ as part of the domain.






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            1 Answer
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            $begingroup$

            Yes, your definition of partial derivative with respect to $y$ at $(x,1)$



            $$ partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$



            is correct. Of course it is one sided because we do not have $y>1$ as part of the domain.






            share|cite|improve this answer









            $endgroup$


















              2












              $begingroup$

              Yes, your definition of partial derivative with respect to $y$ at $(x,1)$



              $$ partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$



              is correct. Of course it is one sided because we do not have $y>1$ as part of the domain.






              share|cite|improve this answer









              $endgroup$
















                2












                2








                2





                $begingroup$

                Yes, your definition of partial derivative with respect to $y$ at $(x,1)$



                $$ partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$



                is correct. Of course it is one sided because we do not have $y>1$ as part of the domain.






                share|cite|improve this answer









                $endgroup$



                Yes, your definition of partial derivative with respect to $y$ at $(x,1)$



                $$ partial_y{u(x, 1)}=lim_{tto 1^{-}}frac{u(x, t) -u(x, 1)}{t-1}$$



                is correct. Of course it is one sided because we do not have $y>1$ as part of the domain.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 4 at 4:06









                Mohammad Riazi-KermaniMohammad Riazi-Kermani

                41.6k42061




                41.6k42061






























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