Continuous function on $[a, b]$ with bounded upper and lower derivatives on $(a, b)$ is Lipschitz. ...

The difference between dialogue marks

Can an undergraduate be advised by a professor who is very far away?

What is preventing me from simply constructing a hash that's lower than the current target?

How to quickly solve partial fractions equation?

How to add class in ko template in magento2

How much of the clove should I use when using big garlic heads?

Is it safe to harvest rainwater that fell on solar panels?

What information about me do stores get via my credit card?

How do I free up internal storage if I don't have any apps downloaded?

If my opponent casts Ultimate Price on my Phantasmal Bear, can I save it by casting Snap or Curfew?

What is the most efficient way to store a numeric range?

Why doesn't UInt have a toDouble()?

Why can't devices on different VLANs, but on the same subnet, communicate?

Why didn't the Event Horizon Telescope team mention Sagittarius A*?

If climate change impact can be observed in nature, has that had any effect on rural, i.e. farming community, perception of the scientific consensus?

Is bread bad for ducks?

Pokemon Turn Based battle (Python)

Does adding complexity mean a more secure cipher?

How to type a long/em dash `—`

How to notate time signature switching consistently every measure

ELI5: Why they say that Israel would have been the fourth country to land a spacecraft on the Moon and why they call it low cost?

Kerning for subscripts of sigma?

How come people say “Would of”?

Can withdrawing asylum be illegal?



Continuous function on $[a, b]$ with bounded upper and lower derivatives on $(a, b)$ is Lipschitz.



The 2019 Stack Overflow Developer Survey Results Are InUpper semi-continuity and lower semi-continuity of particular functionsLipschitz continuity for an iterated function systemThe definition of lim sup at infinityA sequence of functions which are non-uniformly lipschitz with lipschitz limitGreatest Lower Bound of the Set of Upper Bounds for a FunctionRelation between local lipschitz constant and global lipschitz constantShowing that a function is uniformly continuous but not LipschitzApproximation of Lipschitz function in uniform normIf a sequence of unif. cont. Lipschitz functions ${f_n}$ converges unif. to an unif. cont. function f, then f is Lipschitz.Uniform convergence of Lipschitz functions and convergence of their derivatives












0












$begingroup$


This question was posted previously, but without the critical assumption that $f$ be continuous, and so this question was left unanswered.



I am using the following definitions:



Upper derivative of $f$ at $x$:



$overset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystylesup_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$



Lower derivative of $f$ at $x$:



$underset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystyleinf_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$.



My idea is that if, say, $overset{-}{D}$ is bounded then the $sup$ in the definition is finite call it $C$, and we can use this as the constant in the Lipschitz condition. Similarly for $underset{-}{D}$; call its bound $C'$. However, if $underset{-}{D} neq overset{-}{D}$ then $f$ is not differentiable, then these bounds are different. In this case, can I just take $textrm{max} (|C|, |C'|)$ as the Lipschitz constant?



Or am I way off?



PS: as a side question, why do we need $t$ in absolute value in the definitions? Is this because we want to approach from the left as well?










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    This question was posted previously, but without the critical assumption that $f$ be continuous, and so this question was left unanswered.



    I am using the following definitions:



    Upper derivative of $f$ at $x$:



    $overset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystylesup_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$



    Lower derivative of $f$ at $x$:



    $underset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystyleinf_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$.



    My idea is that if, say, $overset{-}{D}$ is bounded then the $sup$ in the definition is finite call it $C$, and we can use this as the constant in the Lipschitz condition. Similarly for $underset{-}{D}$; call its bound $C'$. However, if $underset{-}{D} neq overset{-}{D}$ then $f$ is not differentiable, then these bounds are different. In this case, can I just take $textrm{max} (|C|, |C'|)$ as the Lipschitz constant?



    Or am I way off?



    PS: as a side question, why do we need $t$ in absolute value in the definitions? Is this because we want to approach from the left as well?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      This question was posted previously, but without the critical assumption that $f$ be continuous, and so this question was left unanswered.



      I am using the following definitions:



      Upper derivative of $f$ at $x$:



      $overset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystylesup_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$



      Lower derivative of $f$ at $x$:



      $underset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystyleinf_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$.



      My idea is that if, say, $overset{-}{D}$ is bounded then the $sup$ in the definition is finite call it $C$, and we can use this as the constant in the Lipschitz condition. Similarly for $underset{-}{D}$; call its bound $C'$. However, if $underset{-}{D} neq overset{-}{D}$ then $f$ is not differentiable, then these bounds are different. In this case, can I just take $textrm{max} (|C|, |C'|)$ as the Lipschitz constant?



      Or am I way off?



      PS: as a side question, why do we need $t$ in absolute value in the definitions? Is this because we want to approach from the left as well?










      share|cite|improve this question









      $endgroup$




      This question was posted previously, but without the critical assumption that $f$ be continuous, and so this question was left unanswered.



      I am using the following definitions:



      Upper derivative of $f$ at $x$:



      $overset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystylesup_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$



      Lower derivative of $f$ at $x$:



      $underset{-}{D} , f(x) = displaystyle lim_{h to 0} left [displaystyleinf_{0 < |t|leq h} frac{f(x + t) - f(x)}{t} right ]$.



      My idea is that if, say, $overset{-}{D}$ is bounded then the $sup$ in the definition is finite call it $C$, and we can use this as the constant in the Lipschitz condition. Similarly for $underset{-}{D}$; call its bound $C'$. However, if $underset{-}{D} neq overset{-}{D}$ then $f$ is not differentiable, then these bounds are different. In this case, can I just take $textrm{max} (|C|, |C'|)$ as the Lipschitz constant?



      Or am I way off?



      PS: as a side question, why do we need $t$ in absolute value in the definitions? Is this because we want to approach from the left as well?







      real-analysis






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Mar 22 at 0:20









      JunglemathJunglemath

      1814




      1814






















          0






          active

          oldest

          votes












          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%2f3157573%2fcontinuous-function-on-a-b-with-bounded-upper-and-lower-derivatives-on-a%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          0






          active

          oldest

          votes








          0






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes
















          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%2f3157573%2fcontinuous-function-on-a-b-with-bounded-upper-and-lower-derivatives-on-a%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

          Nidaros erkebispedøme

          Birsay

          Where did Arya get these scars? Unicorn Meta Zoo #1: Why another podcast? Announcing the arrival of Valued Associate #679: Cesar Manara Favourite questions and answers from the 1st quarter of 2019Why did Arya refuse to end it?Has the pronunciation of Arya Stark's name changed?Has Arya forgiven people?Why did Arya Stark lose her vision?Why can Arya still use the faces?Has the Narrow Sea become narrower?Does Arya Stark know how to make poisons outside of the House of Black and White?Why did Nymeria leave Arya?Why did Arya not kill the Lannister soldiers she encountered in the Riverlands?What is the current canonical age of Sansa, Bran and Arya Stark?