Does there exist a function which satisfies follow conditions?












-1












$begingroup$


Does there exist a function which satisfies following conditions?



1) $F(x)=frac{G(x)}{H(x)}$ is a sigmoid function (or S-shaped function);



2) $G(x)$ is strictly concave;



3) $H(x)$ is not a constant.










share|cite|improve this question











$endgroup$

















    -1












    $begingroup$


    Does there exist a function which satisfies following conditions?



    1) $F(x)=frac{G(x)}{H(x)}$ is a sigmoid function (or S-shaped function);



    2) $G(x)$ is strictly concave;



    3) $H(x)$ is not a constant.










    share|cite|improve this question











    $endgroup$















      -1












      -1








      -1


      0



      $begingroup$


      Does there exist a function which satisfies following conditions?



      1) $F(x)=frac{G(x)}{H(x)}$ is a sigmoid function (or S-shaped function);



      2) $G(x)$ is strictly concave;



      3) $H(x)$ is not a constant.










      share|cite|improve this question











      $endgroup$




      Does there exist a function which satisfies following conditions?



      1) $F(x)=frac{G(x)}{H(x)}$ is a sigmoid function (or S-shaped function);



      2) $G(x)$ is strictly concave;



      3) $H(x)$ is not a constant.







      linear-algebra






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Nov 30 '18 at 13:46







      Lee White

















      asked Nov 30 '18 at 12:35









      Lee WhiteLee White

      86




      86






















          1 Answer
          1






          active

          oldest

          votes


















          0












          $begingroup$

          G(x) = log(x+1)



          H(x) = 1+log(x+1)



          F(x) = log(x+1)/(1+log(x+1))



          That works grand



          edit: you edited your question. Your new answer is



          H = log(x+1)/(tanh(x+4)+1)



          G = log(x+1)



          F = tanh(x+4)+1






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:23










          • $begingroup$
            Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
            $endgroup$
            – D'Arcy
            Nov 30 '18 at 13:31






          • 1




            $begingroup$
            Cool, man! I get it! I will try to work as you said, it's a nice method.
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:43













          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%2f3020046%2fdoes-there-exist-a-function-which-satisfies-follow-conditions%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









          0












          $begingroup$

          G(x) = log(x+1)



          H(x) = 1+log(x+1)



          F(x) = log(x+1)/(1+log(x+1))



          That works grand



          edit: you edited your question. Your new answer is



          H = log(x+1)/(tanh(x+4)+1)



          G = log(x+1)



          F = tanh(x+4)+1






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:23










          • $begingroup$
            Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
            $endgroup$
            – D'Arcy
            Nov 30 '18 at 13:31






          • 1




            $begingroup$
            Cool, man! I get it! I will try to work as you said, it's a nice method.
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:43


















          0












          $begingroup$

          G(x) = log(x+1)



          H(x) = 1+log(x+1)



          F(x) = log(x+1)/(1+log(x+1))



          That works grand



          edit: you edited your question. Your new answer is



          H = log(x+1)/(tanh(x+4)+1)



          G = log(x+1)



          F = tanh(x+4)+1






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:23










          • $begingroup$
            Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
            $endgroup$
            – D'Arcy
            Nov 30 '18 at 13:31






          • 1




            $begingroup$
            Cool, man! I get it! I will try to work as you said, it's a nice method.
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:43
















          0












          0








          0





          $begingroup$

          G(x) = log(x+1)



          H(x) = 1+log(x+1)



          F(x) = log(x+1)/(1+log(x+1))



          That works grand



          edit: you edited your question. Your new answer is



          H = log(x+1)/(tanh(x+4)+1)



          G = log(x+1)



          F = tanh(x+4)+1






          share|cite|improve this answer











          $endgroup$



          G(x) = log(x+1)



          H(x) = 1+log(x+1)



          F(x) = log(x+1)/(1+log(x+1))



          That works grand



          edit: you edited your question. Your new answer is



          H = log(x+1)/(tanh(x+4)+1)



          G = log(x+1)



          F = tanh(x+4)+1







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Nov 30 '18 at 13:30

























          answered Nov 30 '18 at 12:52









          D'ArcyD'Arcy

          263




          263












          • $begingroup$
            Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:23










          • $begingroup$
            Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
            $endgroup$
            – D'Arcy
            Nov 30 '18 at 13:31






          • 1




            $begingroup$
            Cool, man! I get it! I will try to work as you said, it's a nice method.
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:43




















          • $begingroup$
            Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:23










          • $begingroup$
            Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
            $endgroup$
            – D'Arcy
            Nov 30 '18 at 13:31






          • 1




            $begingroup$
            Cool, man! I get it! I will try to work as you said, it's a nice method.
            $endgroup$
            – Lee White
            Nov 30 '18 at 13:43


















          $begingroup$
          Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
          $endgroup$
          – Lee White
          Nov 30 '18 at 13:23




          $begingroup$
          Thanks for your answers. But I can't fully understand the functions you offered. The first function, referred to as $F1$, indeed works when $x in [0,infty]$, which I can understand. But the second one, $F2=1/(tanh(x+4)+1)$, is this a sigmoid function?
          $endgroup$
          – Lee White
          Nov 30 '18 at 13:23












          $begingroup$
          Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
          $endgroup$
          – D'Arcy
          Nov 30 '18 at 13:31




          $begingroup$
          Yep, I had a typo in there, basically F can be any sigmoid function you like, just make G random concave function, and H the inverse of a sigmoid times G
          $endgroup$
          – D'Arcy
          Nov 30 '18 at 13:31




          1




          1




          $begingroup$
          Cool, man! I get it! I will try to work as you said, it's a nice method.
          $endgroup$
          – Lee White
          Nov 30 '18 at 13:43






          $begingroup$
          Cool, man! I get it! I will try to work as you said, it's a nice method.
          $endgroup$
          – Lee White
          Nov 30 '18 at 13:43




















          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%2f3020046%2fdoes-there-exist-a-function-which-satisfies-follow-conditions%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

          Plaza Victoria

          Puebla de Zaragoza

          Musa