Inverse of matrix expansion with negative exponents












0












$begingroup$


The answer to this question shows that if I have a real nonsingular matrix $M$, such that its Taylor expansion in $epsilon$ is



$$M(x+epsilon)= sum_{n=0}^infty M_n(x) epsilon^n $$



its inverse can be written as an expansion using the following formula



$$B = sum_{i=0}^infty b_nepsilon^n$$



$$b_0 = a_0^{-1},$$
$$b_1 = -a_0^{-1}a_1a_0^{-1}$$
$$b_2 = a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} -a_0^{-1}a_2a_0^{-1}$$
$$b_3 = - a_0^{-1}a_1a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} + a_0^{-1}a_1a_0^{-1}a_2a_0^{-1} + a_0^{-1}a_2a_0^{-1}a_1a_0^{-1} - a_0^{-1}a_3a_0^{-1}$$



My question is: how does this change if I also have negative powers of $epsilon$ in the expansion? i.e.



$$mathcal{M}(x)=sum_{n=-infty}^infty mathcal{M}_n(x)epsilon^n$$










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    The answer to this question shows that if I have a real nonsingular matrix $M$, such that its Taylor expansion in $epsilon$ is



    $$M(x+epsilon)= sum_{n=0}^infty M_n(x) epsilon^n $$



    its inverse can be written as an expansion using the following formula



    $$B = sum_{i=0}^infty b_nepsilon^n$$



    $$b_0 = a_0^{-1},$$
    $$b_1 = -a_0^{-1}a_1a_0^{-1}$$
    $$b_2 = a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} -a_0^{-1}a_2a_0^{-1}$$
    $$b_3 = - a_0^{-1}a_1a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} + a_0^{-1}a_1a_0^{-1}a_2a_0^{-1} + a_0^{-1}a_2a_0^{-1}a_1a_0^{-1} - a_0^{-1}a_3a_0^{-1}$$



    My question is: how does this change if I also have negative powers of $epsilon$ in the expansion? i.e.



    $$mathcal{M}(x)=sum_{n=-infty}^infty mathcal{M}_n(x)epsilon^n$$










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      The answer to this question shows that if I have a real nonsingular matrix $M$, such that its Taylor expansion in $epsilon$ is



      $$M(x+epsilon)= sum_{n=0}^infty M_n(x) epsilon^n $$



      its inverse can be written as an expansion using the following formula



      $$B = sum_{i=0}^infty b_nepsilon^n$$



      $$b_0 = a_0^{-1},$$
      $$b_1 = -a_0^{-1}a_1a_0^{-1}$$
      $$b_2 = a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} -a_0^{-1}a_2a_0^{-1}$$
      $$b_3 = - a_0^{-1}a_1a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} + a_0^{-1}a_1a_0^{-1}a_2a_0^{-1} + a_0^{-1}a_2a_0^{-1}a_1a_0^{-1} - a_0^{-1}a_3a_0^{-1}$$



      My question is: how does this change if I also have negative powers of $epsilon$ in the expansion? i.e.



      $$mathcal{M}(x)=sum_{n=-infty}^infty mathcal{M}_n(x)epsilon^n$$










      share|cite|improve this question









      $endgroup$




      The answer to this question shows that if I have a real nonsingular matrix $M$, such that its Taylor expansion in $epsilon$ is



      $$M(x+epsilon)= sum_{n=0}^infty M_n(x) epsilon^n $$



      its inverse can be written as an expansion using the following formula



      $$B = sum_{i=0}^infty b_nepsilon^n$$



      $$b_0 = a_0^{-1},$$
      $$b_1 = -a_0^{-1}a_1a_0^{-1}$$
      $$b_2 = a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} -a_0^{-1}a_2a_0^{-1}$$
      $$b_3 = - a_0^{-1}a_1a_0^{-1}a_1a_0^{-1}a_1a_0^{-1} + a_0^{-1}a_1a_0^{-1}a_2a_0^{-1} + a_0^{-1}a_2a_0^{-1}a_1a_0^{-1} - a_0^{-1}a_3a_0^{-1}$$



      My question is: how does this change if I also have negative powers of $epsilon$ in the expansion? i.e.



      $$mathcal{M}(x)=sum_{n=-infty}^infty mathcal{M}_n(x)epsilon^n$$







      matrices power-series taylor-expansion inverse matrix-calculus






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 16 at 15:11









      usumdelphiniusumdelphini

      323111




      323111






















          1 Answer
          1






          active

          oldest

          votes


















          2












          $begingroup$

          If you define $M(x)$ as a Cauchy principal value, that is, $M(x)=lim_{krightarrow +infty}sum_{n=-k}^k M_n(x)epsilon^n$, then



          $M(x)=sum_{n=0}^{+infty}U_n(x)epsilon^n$ where $U_0=M_0,U_{2p}=M_{2p}+M_{-2p},U_{2p+1}=M_{2p+1}-M_{-2p-1}$.






          share|cite|improve this answer









          $endgroup$














            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',
            autoActivateHeartbeat: false,
            convertImagesToLinks: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            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%2f3075846%2finverse-of-matrix-expansion-with-negative-exponents%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            2












            $begingroup$

            If you define $M(x)$ as a Cauchy principal value, that is, $M(x)=lim_{krightarrow +infty}sum_{n=-k}^k M_n(x)epsilon^n$, then



            $M(x)=sum_{n=0}^{+infty}U_n(x)epsilon^n$ where $U_0=M_0,U_{2p}=M_{2p}+M_{-2p},U_{2p+1}=M_{2p+1}-M_{-2p-1}$.






            share|cite|improve this answer









            $endgroup$


















              2












              $begingroup$

              If you define $M(x)$ as a Cauchy principal value, that is, $M(x)=lim_{krightarrow +infty}sum_{n=-k}^k M_n(x)epsilon^n$, then



              $M(x)=sum_{n=0}^{+infty}U_n(x)epsilon^n$ where $U_0=M_0,U_{2p}=M_{2p}+M_{-2p},U_{2p+1}=M_{2p+1}-M_{-2p-1}$.






              share|cite|improve this answer









              $endgroup$
















                2












                2








                2





                $begingroup$

                If you define $M(x)$ as a Cauchy principal value, that is, $M(x)=lim_{krightarrow +infty}sum_{n=-k}^k M_n(x)epsilon^n$, then



                $M(x)=sum_{n=0}^{+infty}U_n(x)epsilon^n$ where $U_0=M_0,U_{2p}=M_{2p}+M_{-2p},U_{2p+1}=M_{2p+1}-M_{-2p-1}$.






                share|cite|improve this answer









                $endgroup$



                If you define $M(x)$ as a Cauchy principal value, that is, $M(x)=lim_{krightarrow +infty}sum_{n=-k}^k M_n(x)epsilon^n$, then



                $M(x)=sum_{n=0}^{+infty}U_n(x)epsilon^n$ where $U_0=M_0,U_{2p}=M_{2p}+M_{-2p},U_{2p+1}=M_{2p+1}-M_{-2p-1}$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 27 at 11:18









                loup blancloup blanc

                24.1k21851




                24.1k21851






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Mathematics Stack Exchange!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    Use MathJax to format equations. MathJax reference.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3075846%2finverse-of-matrix-expansion-with-negative-exponents%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    Popular posts from this blog

                    Human spaceflight

                    Can not write log (Is /dev/pts mounted?) - openpty in Ubuntu-on-Windows?

                    File:DeusFollowingSea.jpg