transpose of positive matrix is positive












4












$begingroup$


how to prove it?



I am talking about matrixes which satisfy:



$$( Ax , x ) > 0quad text{ for any}quad ;x neq 0.$$



How to prove that $A^T;$ is also positive?



$$x^T A x = ( x^T A x )^T$$



and what?










share|cite|improve this question











$endgroup$

















    4












    $begingroup$


    how to prove it?



    I am talking about matrixes which satisfy:



    $$( Ax , x ) > 0quad text{ for any}quad ;x neq 0.$$



    How to prove that $A^T;$ is also positive?



    $$x^T A x = ( x^T A x )^T$$



    and what?










    share|cite|improve this question











    $endgroup$















      4












      4








      4





      $begingroup$


      how to prove it?



      I am talking about matrixes which satisfy:



      $$( Ax , x ) > 0quad text{ for any}quad ;x neq 0.$$



      How to prove that $A^T;$ is also positive?



      $$x^T A x = ( x^T A x )^T$$



      and what?










      share|cite|improve this question











      $endgroup$




      how to prove it?



      I am talking about matrixes which satisfy:



      $$( Ax , x ) > 0quad text{ for any}quad ;x neq 0.$$



      How to prove that $A^T;$ is also positive?



      $$x^T A x = ( x^T A x )^T$$



      and what?







      linear-algebra matrices






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 1 at 21:45









      user376343

      3,9584829




      3,9584829










      asked Jan 17 '11 at 8:53









      mr. Vachovskymr. Vachovsky

      1214




      1214






















          1 Answer
          1






          active

          oldest

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          7












          $begingroup$

          Hint: Write the inner product as $x^T A x$ and use the fact that that expression is its own transpose (since it's a 1-by-1 matrix).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thx, I understood!
            $endgroup$
            – mr. Vachovsky
            Jan 17 '11 at 9:08












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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          7












          $begingroup$

          Hint: Write the inner product as $x^T A x$ and use the fact that that expression is its own transpose (since it's a 1-by-1 matrix).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thx, I understood!
            $endgroup$
            – mr. Vachovsky
            Jan 17 '11 at 9:08
















          7












          $begingroup$

          Hint: Write the inner product as $x^T A x$ and use the fact that that expression is its own transpose (since it's a 1-by-1 matrix).






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thx, I understood!
            $endgroup$
            – mr. Vachovsky
            Jan 17 '11 at 9:08














          7












          7








          7





          $begingroup$

          Hint: Write the inner product as $x^T A x$ and use the fact that that expression is its own transpose (since it's a 1-by-1 matrix).






          share|cite|improve this answer









          $endgroup$



          Hint: Write the inner product as $x^T A x$ and use the fact that that expression is its own transpose (since it's a 1-by-1 matrix).







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 17 '11 at 8:55









          Hans LundmarkHans Lundmark

          36k564115




          36k564115












          • $begingroup$
            Thx, I understood!
            $endgroup$
            – mr. Vachovsky
            Jan 17 '11 at 9:08


















          • $begingroup$
            Thx, I understood!
            $endgroup$
            – mr. Vachovsky
            Jan 17 '11 at 9:08
















          $begingroup$
          Thx, I understood!
          $endgroup$
          – mr. Vachovsky
          Jan 17 '11 at 9:08




          $begingroup$
          Thx, I understood!
          $endgroup$
          – mr. Vachovsky
          Jan 17 '11 at 9:08


















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