What is the meaning of notation $ nabla u + nabla u^T$?












1












$begingroup$


In my exercises it appears ($u:mathbb{R}^3rightarrowmathbb{R}^3$):



$$ nabla u + nabla u^T$$



What is the meaning of this notation when writing it in terms of partials of $u_i$?










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$endgroup$

















    1












    $begingroup$


    In my exercises it appears ($u:mathbb{R}^3rightarrowmathbb{R}^3$):



    $$ nabla u + nabla u^T$$



    What is the meaning of this notation when writing it in terms of partials of $u_i$?










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      In my exercises it appears ($u:mathbb{R}^3rightarrowmathbb{R}^3$):



      $$ nabla u + nabla u^T$$



      What is the meaning of this notation when writing it in terms of partials of $u_i$?










      share|cite|improve this question











      $endgroup$




      In my exercises it appears ($u:mathbb{R}^3rightarrowmathbb{R}^3$):



      $$ nabla u + nabla u^T$$



      What is the meaning of this notation when writing it in terms of partials of $u_i$?







      notation vector-analysis






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      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Dec 19 '18 at 20:51









      Jean Marie

      30.9k42155




      30.9k42155










      asked Dec 19 '18 at 19:24









      davidivadfuldavidivadful

      13610




      13610






















          2 Answers
          2






          active

          oldest

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          3












          $begingroup$

          Typically, when $u:Bbb R^3 to Bbb R^3$, we define
          $$
          newcommand{pwrt}[2]{frac{partial #1}{partial #2}}\
          nabla u = pmatrix{pwrt {u_1}{x_1} & pwrt {u_1}{x_2} & pwrt {u_1}{x_3}\
          pwrt {u_2}{x_1} & pwrt {u_2}{x_2} & pwrt {u_2}{x_3}\
          pwrt {u_3}{x_1} & pwrt {u_3}{x_2} & pwrt {u_3}{x_3}\}
          $$

          In some contexts, this is referred to instead as the Jacobian of $u$.



          $M^T$ refers to the transpose of the matrix $M$.






          share|cite|improve this answer









          $endgroup$





















            2












            $begingroup$

            $M=nabla u ; ;$ is a $(3times 3)$ matrix
            with
            $$M_{i,j}=frac{partial u_i}{partial x_j}$$



            and



            $$nabla u^T=M^T=N$$
            with
            $$N_{i,j}=M_{j,i}=frac{partial u_j}{partial x_i}$$ is the transpose matrix of $M$.






            share|cite|improve this answer











            $endgroup$













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              2 Answers
              2






              active

              oldest

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              2 Answers
              2






              active

              oldest

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              active

              oldest

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              active

              oldest

              votes









              3












              $begingroup$

              Typically, when $u:Bbb R^3 to Bbb R^3$, we define
              $$
              newcommand{pwrt}[2]{frac{partial #1}{partial #2}}\
              nabla u = pmatrix{pwrt {u_1}{x_1} & pwrt {u_1}{x_2} & pwrt {u_1}{x_3}\
              pwrt {u_2}{x_1} & pwrt {u_2}{x_2} & pwrt {u_2}{x_3}\
              pwrt {u_3}{x_1} & pwrt {u_3}{x_2} & pwrt {u_3}{x_3}\}
              $$

              In some contexts, this is referred to instead as the Jacobian of $u$.



              $M^T$ refers to the transpose of the matrix $M$.






              share|cite|improve this answer









              $endgroup$


















                3












                $begingroup$

                Typically, when $u:Bbb R^3 to Bbb R^3$, we define
                $$
                newcommand{pwrt}[2]{frac{partial #1}{partial #2}}\
                nabla u = pmatrix{pwrt {u_1}{x_1} & pwrt {u_1}{x_2} & pwrt {u_1}{x_3}\
                pwrt {u_2}{x_1} & pwrt {u_2}{x_2} & pwrt {u_2}{x_3}\
                pwrt {u_3}{x_1} & pwrt {u_3}{x_2} & pwrt {u_3}{x_3}\}
                $$

                In some contexts, this is referred to instead as the Jacobian of $u$.



                $M^T$ refers to the transpose of the matrix $M$.






                share|cite|improve this answer









                $endgroup$
















                  3












                  3








                  3





                  $begingroup$

                  Typically, when $u:Bbb R^3 to Bbb R^3$, we define
                  $$
                  newcommand{pwrt}[2]{frac{partial #1}{partial #2}}\
                  nabla u = pmatrix{pwrt {u_1}{x_1} & pwrt {u_1}{x_2} & pwrt {u_1}{x_3}\
                  pwrt {u_2}{x_1} & pwrt {u_2}{x_2} & pwrt {u_2}{x_3}\
                  pwrt {u_3}{x_1} & pwrt {u_3}{x_2} & pwrt {u_3}{x_3}\}
                  $$

                  In some contexts, this is referred to instead as the Jacobian of $u$.



                  $M^T$ refers to the transpose of the matrix $M$.






                  share|cite|improve this answer









                  $endgroup$



                  Typically, when $u:Bbb R^3 to Bbb R^3$, we define
                  $$
                  newcommand{pwrt}[2]{frac{partial #1}{partial #2}}\
                  nabla u = pmatrix{pwrt {u_1}{x_1} & pwrt {u_1}{x_2} & pwrt {u_1}{x_3}\
                  pwrt {u_2}{x_1} & pwrt {u_2}{x_2} & pwrt {u_2}{x_3}\
                  pwrt {u_3}{x_1} & pwrt {u_3}{x_2} & pwrt {u_3}{x_3}\}
                  $$

                  In some contexts, this is referred to instead as the Jacobian of $u$.



                  $M^T$ refers to the transpose of the matrix $M$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 19 '18 at 19:30









                  OmnomnomnomOmnomnomnom

                  129k792185




                  129k792185























                      2












                      $begingroup$

                      $M=nabla u ; ;$ is a $(3times 3)$ matrix
                      with
                      $$M_{i,j}=frac{partial u_i}{partial x_j}$$



                      and



                      $$nabla u^T=M^T=N$$
                      with
                      $$N_{i,j}=M_{j,i}=frac{partial u_j}{partial x_i}$$ is the transpose matrix of $M$.






                      share|cite|improve this answer











                      $endgroup$


















                        2












                        $begingroup$

                        $M=nabla u ; ;$ is a $(3times 3)$ matrix
                        with
                        $$M_{i,j}=frac{partial u_i}{partial x_j}$$



                        and



                        $$nabla u^T=M^T=N$$
                        with
                        $$N_{i,j}=M_{j,i}=frac{partial u_j}{partial x_i}$$ is the transpose matrix of $M$.






                        share|cite|improve this answer











                        $endgroup$
















                          2












                          2








                          2





                          $begingroup$

                          $M=nabla u ; ;$ is a $(3times 3)$ matrix
                          with
                          $$M_{i,j}=frac{partial u_i}{partial x_j}$$



                          and



                          $$nabla u^T=M^T=N$$
                          with
                          $$N_{i,j}=M_{j,i}=frac{partial u_j}{partial x_i}$$ is the transpose matrix of $M$.






                          share|cite|improve this answer











                          $endgroup$



                          $M=nabla u ; ;$ is a $(3times 3)$ matrix
                          with
                          $$M_{i,j}=frac{partial u_i}{partial x_j}$$



                          and



                          $$nabla u^T=M^T=N$$
                          with
                          $$N_{i,j}=M_{j,i}=frac{partial u_j}{partial x_i}$$ is the transpose matrix of $M$.







                          share|cite|improve this answer














                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited Dec 19 '18 at 20:05

























                          answered Dec 19 '18 at 19:31









                          hamam_Abdallahhamam_Abdallah

                          38.2k21634




                          38.2k21634






























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