For real square matrices of the same dimension, does the following hold?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
1
down vote

favorite












Given real square matrices $A_1,A_2$ of the same dimension, does the following inequality hold?



$e^A^T_1e^A^T_2e^A_2e^A_1leqe^A_1+A_2+A^T_1+A^T_2$



where $A^T_i$ stands for the transpose of $A_i$ and $leq$ denotes the negative semi-definiteness of the left argument with respect to right. I know if $A_1,A_2$ commute and both matrices are normal, then



$e^A^T_1e^A^T_2e^A_2e^A_1=e^A_1+A_2+A^T_1+A^T_2$. But I am not sure if the inequality mentioned above holds.



Any suggestions, hints or references relating to the results on similar matrix exponential inequalities are greatly appreciated.










share|cite|improve this question

























    up vote
    1
    down vote

    favorite












    Given real square matrices $A_1,A_2$ of the same dimension, does the following inequality hold?



    $e^A^T_1e^A^T_2e^A_2e^A_1leqe^A_1+A_2+A^T_1+A^T_2$



    where $A^T_i$ stands for the transpose of $A_i$ and $leq$ denotes the negative semi-definiteness of the left argument with respect to right. I know if $A_1,A_2$ commute and both matrices are normal, then



    $e^A^T_1e^A^T_2e^A_2e^A_1=e^A_1+A_2+A^T_1+A^T_2$. But I am not sure if the inequality mentioned above holds.



    Any suggestions, hints or references relating to the results on similar matrix exponential inequalities are greatly appreciated.










    share|cite|improve this question























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      Given real square matrices $A_1,A_2$ of the same dimension, does the following inequality hold?



      $e^A^T_1e^A^T_2e^A_2e^A_1leqe^A_1+A_2+A^T_1+A^T_2$



      where $A^T_i$ stands for the transpose of $A_i$ and $leq$ denotes the negative semi-definiteness of the left argument with respect to right. I know if $A_1,A_2$ commute and both matrices are normal, then



      $e^A^T_1e^A^T_2e^A_2e^A_1=e^A_1+A_2+A^T_1+A^T_2$. But I am not sure if the inequality mentioned above holds.



      Any suggestions, hints or references relating to the results on similar matrix exponential inequalities are greatly appreciated.










      share|cite|improve this question













      Given real square matrices $A_1,A_2$ of the same dimension, does the following inequality hold?



      $e^A^T_1e^A^T_2e^A_2e^A_1leqe^A_1+A_2+A^T_1+A^T_2$



      where $A^T_i$ stands for the transpose of $A_i$ and $leq$ denotes the negative semi-definiteness of the left argument with respect to right. I know if $A_1,A_2$ commute and both matrices are normal, then



      $e^A^T_1e^A^T_2e^A_2e^A_1=e^A_1+A_2+A^T_1+A^T_2$. But I am not sure if the inequality mentioned above holds.



      Any suggestions, hints or references relating to the results on similar matrix exponential inequalities are greatly appreciated.







      linear-algebra matrices matrix-calculus matrix-decomposition matrix-exponential






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Aug 30 at 0:26









      jbgujgu

      9210




      9210




















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          1
          down vote



          accepted










          It's false. Take $A_1=0_2,A_2=beginpmatrix-7.2&-3.2\-0.2&-7.4endpmatrix$.






          share|cite|improve this answer




















            Your Answer




            StackExchange.ifUsing("editor", function ()
            return StackExchange.using("mathjaxEditing", function ()
            StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
            StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
            );
            );
            , "mathjax-editing");

            StackExchange.ready(function()
            var channelOptions =
            tags: "".split(" "),
            id: "69"
            ;
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function()
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled)
            StackExchange.using("snippets", function()
            createEditor();
            );

            else
            createEditor();

            );

            function createEditor()
            StackExchange.prepareEditor(
            heartbeatType: 'answer',
            convertImagesToLinks: true,
            noModals: false,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            noCode: true, onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            );



            );













             

            draft saved


            draft discarded


















            StackExchange.ready(
            function ()
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2898965%2ffor-real-square-matrices-of-the-same-dimension-does-the-following-hold%23new-answer', 'question_page');

            );

            Post as a guest






























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            It's false. Take $A_1=0_2,A_2=beginpmatrix-7.2&-3.2\-0.2&-7.4endpmatrix$.






            share|cite|improve this answer
























              up vote
              1
              down vote



              accepted










              It's false. Take $A_1=0_2,A_2=beginpmatrix-7.2&-3.2\-0.2&-7.4endpmatrix$.






              share|cite|improve this answer






















                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                It's false. Take $A_1=0_2,A_2=beginpmatrix-7.2&-3.2\-0.2&-7.4endpmatrix$.






                share|cite|improve this answer












                It's false. Take $A_1=0_2,A_2=beginpmatrix-7.2&-3.2\-0.2&-7.4endpmatrix$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Sep 3 at 13:16









                loup blanc

                20.6k21649




                20.6k21649



























                     

                    draft saved


                    draft discarded















































                     


                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function ()
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2898965%2ffor-real-square-matrices-of-the-same-dimension-does-the-following-hold%23new-answer', 'question_page');

                    );

                    Post as a guest













































































                    這個網誌中的熱門文章

                    tkz-euclide: tkzDrawCircle[R] not working

                    How to combine Bézier curves to a surface?

                    1st Magritte Awards