Outer Product of Two Matrices?












13












$begingroup$


How would I go about calculating the outer product of two matrices of 2 dimensions each? From what I can find, outer product seems to be the product of two vectors, $u$ and the transpose of another vector, $v^T$.



As an example, how would I calculate the outer product of $A$ and $B$, where
$$A = begin{pmatrix}1 & 2 \ 3 & 4end{pmatrix} qquad B = begin{pmatrix}5 & 6 & 7 \ 8 & 9 & 10end{pmatrix}$$










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    13












    $begingroup$


    How would I go about calculating the outer product of two matrices of 2 dimensions each? From what I can find, outer product seems to be the product of two vectors, $u$ and the transpose of another vector, $v^T$.



    As an example, how would I calculate the outer product of $A$ and $B$, where
    $$A = begin{pmatrix}1 & 2 \ 3 & 4end{pmatrix} qquad B = begin{pmatrix}5 & 6 & 7 \ 8 & 9 & 10end{pmatrix}$$










    share|cite|improve this question











    $endgroup$















      13












      13








      13


      4



      $begingroup$


      How would I go about calculating the outer product of two matrices of 2 dimensions each? From what I can find, outer product seems to be the product of two vectors, $u$ and the transpose of another vector, $v^T$.



      As an example, how would I calculate the outer product of $A$ and $B$, where
      $$A = begin{pmatrix}1 & 2 \ 3 & 4end{pmatrix} qquad B = begin{pmatrix}5 & 6 & 7 \ 8 & 9 & 10end{pmatrix}$$










      share|cite|improve this question











      $endgroup$




      How would I go about calculating the outer product of two matrices of 2 dimensions each? From what I can find, outer product seems to be the product of two vectors, $u$ and the transpose of another vector, $v^T$.



      As an example, how would I calculate the outer product of $A$ and $B$, where
      $$A = begin{pmatrix}1 & 2 \ 3 & 4end{pmatrix} qquad B = begin{pmatrix}5 & 6 & 7 \ 8 & 9 & 10end{pmatrix}$$







      matrices tensor-products






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      edited Oct 14 '14 at 16:25









      davcha

      1,062417




      1,062417










      asked Oct 14 '14 at 16:17









      user2049004user2049004

      3441313




      3441313






















          2 Answers
          2






          active

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          15












          $begingroup$

          The outer product usually refers to the tensor product of vectors.
          If you want something like the outer product between a $m times n$ matrix $A$ and a $ptimes q$ matrix $B$, you can see the generalization of outer product, which is the kronecker product. It is noted $A otimes B$ and equals:
          $$A otimes B = begin{pmatrix}a_{11}B & dots & a_{1n}B \ vdots & ddots & vdots \ a_{m1}B & dots & a_{mn}Bend{pmatrix}$$






          share|cite|improve this answer











          $endgroup$





















            11












            $begingroup$

            To extend davcha's answer, for your specific example, you would get:



            $$Aotimes B=
            left(
            begin{array}{cc}
            left(
            begin{array}{ccc}
            5 & 6 & 7 \
            8 & 9 & 10 \
            end{array}
            right) & left(
            begin{array}{ccc}
            10 & 12 & 14 \
            16 & 18 & 20 \
            end{array}
            right) \
            left(
            begin{array}{ccc}
            15 & 18 & 21 \
            24 & 27 & 30 \
            end{array}
            right) & left(
            begin{array}{ccc}
            20 & 24 & 28 \
            32 & 36 & 40 \
            end{array}
            right) \
            end{array}
            right)
            $$






            share|cite|improve this answer









            $endgroup$













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              2 Answers
              2






              active

              oldest

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              2 Answers
              2






              active

              oldest

              votes









              active

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              active

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              15












              $begingroup$

              The outer product usually refers to the tensor product of vectors.
              If you want something like the outer product between a $m times n$ matrix $A$ and a $ptimes q$ matrix $B$, you can see the generalization of outer product, which is the kronecker product. It is noted $A otimes B$ and equals:
              $$A otimes B = begin{pmatrix}a_{11}B & dots & a_{1n}B \ vdots & ddots & vdots \ a_{m1}B & dots & a_{mn}Bend{pmatrix}$$






              share|cite|improve this answer











              $endgroup$


















                15












                $begingroup$

                The outer product usually refers to the tensor product of vectors.
                If you want something like the outer product between a $m times n$ matrix $A$ and a $ptimes q$ matrix $B$, you can see the generalization of outer product, which is the kronecker product. It is noted $A otimes B$ and equals:
                $$A otimes B = begin{pmatrix}a_{11}B & dots & a_{1n}B \ vdots & ddots & vdots \ a_{m1}B & dots & a_{mn}Bend{pmatrix}$$






                share|cite|improve this answer











                $endgroup$
















                  15












                  15








                  15





                  $begingroup$

                  The outer product usually refers to the tensor product of vectors.
                  If you want something like the outer product between a $m times n$ matrix $A$ and a $ptimes q$ matrix $B$, you can see the generalization of outer product, which is the kronecker product. It is noted $A otimes B$ and equals:
                  $$A otimes B = begin{pmatrix}a_{11}B & dots & a_{1n}B \ vdots & ddots & vdots \ a_{m1}B & dots & a_{mn}Bend{pmatrix}$$






                  share|cite|improve this answer











                  $endgroup$



                  The outer product usually refers to the tensor product of vectors.
                  If you want something like the outer product between a $m times n$ matrix $A$ and a $ptimes q$ matrix $B$, you can see the generalization of outer product, which is the kronecker product. It is noted $A otimes B$ and equals:
                  $$A otimes B = begin{pmatrix}a_{11}B & dots & a_{1n}B \ vdots & ddots & vdots \ a_{m1}B & dots & a_{mn}Bend{pmatrix}$$







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Oct 14 '14 at 16:39

























                  answered Oct 14 '14 at 16:34









                  davchadavcha

                  1,062417




                  1,062417























                      11












                      $begingroup$

                      To extend davcha's answer, for your specific example, you would get:



                      $$Aotimes B=
                      left(
                      begin{array}{cc}
                      left(
                      begin{array}{ccc}
                      5 & 6 & 7 \
                      8 & 9 & 10 \
                      end{array}
                      right) & left(
                      begin{array}{ccc}
                      10 & 12 & 14 \
                      16 & 18 & 20 \
                      end{array}
                      right) \
                      left(
                      begin{array}{ccc}
                      15 & 18 & 21 \
                      24 & 27 & 30 \
                      end{array}
                      right) & left(
                      begin{array}{ccc}
                      20 & 24 & 28 \
                      32 & 36 & 40 \
                      end{array}
                      right) \
                      end{array}
                      right)
                      $$






                      share|cite|improve this answer









                      $endgroup$


















                        11












                        $begingroup$

                        To extend davcha's answer, for your specific example, you would get:



                        $$Aotimes B=
                        left(
                        begin{array}{cc}
                        left(
                        begin{array}{ccc}
                        5 & 6 & 7 \
                        8 & 9 & 10 \
                        end{array}
                        right) & left(
                        begin{array}{ccc}
                        10 & 12 & 14 \
                        16 & 18 & 20 \
                        end{array}
                        right) \
                        left(
                        begin{array}{ccc}
                        15 & 18 & 21 \
                        24 & 27 & 30 \
                        end{array}
                        right) & left(
                        begin{array}{ccc}
                        20 & 24 & 28 \
                        32 & 36 & 40 \
                        end{array}
                        right) \
                        end{array}
                        right)
                        $$






                        share|cite|improve this answer









                        $endgroup$
















                          11












                          11








                          11





                          $begingroup$

                          To extend davcha's answer, for your specific example, you would get:



                          $$Aotimes B=
                          left(
                          begin{array}{cc}
                          left(
                          begin{array}{ccc}
                          5 & 6 & 7 \
                          8 & 9 & 10 \
                          end{array}
                          right) & left(
                          begin{array}{ccc}
                          10 & 12 & 14 \
                          16 & 18 & 20 \
                          end{array}
                          right) \
                          left(
                          begin{array}{ccc}
                          15 & 18 & 21 \
                          24 & 27 & 30 \
                          end{array}
                          right) & left(
                          begin{array}{ccc}
                          20 & 24 & 28 \
                          32 & 36 & 40 \
                          end{array}
                          right) \
                          end{array}
                          right)
                          $$






                          share|cite|improve this answer









                          $endgroup$



                          To extend davcha's answer, for your specific example, you would get:



                          $$Aotimes B=
                          left(
                          begin{array}{cc}
                          left(
                          begin{array}{ccc}
                          5 & 6 & 7 \
                          8 & 9 & 10 \
                          end{array}
                          right) & left(
                          begin{array}{ccc}
                          10 & 12 & 14 \
                          16 & 18 & 20 \
                          end{array}
                          right) \
                          left(
                          begin{array}{ccc}
                          15 & 18 & 21 \
                          24 & 27 & 30 \
                          end{array}
                          right) & left(
                          begin{array}{ccc}
                          20 & 24 & 28 \
                          32 & 36 & 40 \
                          end{array}
                          right) \
                          end{array}
                          right)
                          $$







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Nov 1 '15 at 13:58









                          Sandu UrsuSandu Ursu

                          183114




                          183114






























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