Proving $f(x,y)=left ( frac{1}{4}sin(x+y),1+frac{2}{3}arctan(x-y) right )$ is a contraction












0












$begingroup$


$f(x,y)=left ( frac{1}{4}sin(x+y),1+frac{2}{3}arctan(x-y) right )$



Prove that $f$ is a contraction



$mathbb{R}^2$ is equipped with $d((x,y),(x',y'))=|x-x'|+|y-y'|$



My problem is that I'm not able to find an upper bound of $|sin(x+y)-sin(x'+y')|$










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$endgroup$

















    0












    $begingroup$


    $f(x,y)=left ( frac{1}{4}sin(x+y),1+frac{2}{3}arctan(x-y) right )$



    Prove that $f$ is a contraction



    $mathbb{R}^2$ is equipped with $d((x,y),(x',y'))=|x-x'|+|y-y'|$



    My problem is that I'm not able to find an upper bound of $|sin(x+y)-sin(x'+y')|$










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      $f(x,y)=left ( frac{1}{4}sin(x+y),1+frac{2}{3}arctan(x-y) right )$



      Prove that $f$ is a contraction



      $mathbb{R}^2$ is equipped with $d((x,y),(x',y'))=|x-x'|+|y-y'|$



      My problem is that I'm not able to find an upper bound of $|sin(x+y)-sin(x'+y')|$










      share|cite|improve this question











      $endgroup$




      $f(x,y)=left ( frac{1}{4}sin(x+y),1+frac{2}{3}arctan(x-y) right )$



      Prove that $f$ is a contraction



      $mathbb{R}^2$ is equipped with $d((x,y),(x',y'))=|x-x'|+|y-y'|$



      My problem is that I'm not able to find an upper bound of $|sin(x+y)-sin(x'+y')|$







      general-topology






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 16 at 3:29









      Andrews

      5191318




      5191318










      asked Jan 16 at 0:29









      Pedro AlvarèsPedro Alvarès

      636




      636






















          1 Answer
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          0












          $begingroup$

          By MVT $|sin(A)-sin(B)|leq |A-B|$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            But A is a function of x and y
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37










          • $begingroup$
            Then what is ther derivative if sin(A)
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37











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          1 Answer
          1






          active

          oldest

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          active

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          active

          oldest

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          0












          $begingroup$

          By MVT $|sin(A)-sin(B)|leq |A-B|$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            But A is a function of x and y
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37










          • $begingroup$
            Then what is ther derivative if sin(A)
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37
















          0












          $begingroup$

          By MVT $|sin(A)-sin(B)|leq |A-B|$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            But A is a function of x and y
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37










          • $begingroup$
            Then what is ther derivative if sin(A)
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37














          0












          0








          0





          $begingroup$

          By MVT $|sin(A)-sin(B)|leq |A-B|$.






          share|cite|improve this answer









          $endgroup$



          By MVT $|sin(A)-sin(B)|leq |A-B|$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 16 at 0:32









          Kavi Rama MurthyKavi Rama Murthy

          61.6k42262




          61.6k42262












          • $begingroup$
            But A is a function of x and y
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37










          • $begingroup$
            Then what is ther derivative if sin(A)
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37


















          • $begingroup$
            But A is a function of x and y
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37










          • $begingroup$
            Then what is ther derivative if sin(A)
            $endgroup$
            – Pedro Alvarès
            Jan 16 at 0:37
















          $begingroup$
          But A is a function of x and y
          $endgroup$
          – Pedro Alvarès
          Jan 16 at 0:37




          $begingroup$
          But A is a function of x and y
          $endgroup$
          – Pedro Alvarès
          Jan 16 at 0:37












          $begingroup$
          Then what is ther derivative if sin(A)
          $endgroup$
          – Pedro Alvarès
          Jan 16 at 0:37




          $begingroup$
          Then what is ther derivative if sin(A)
          $endgroup$
          – Pedro Alvarès
          Jan 16 at 0:37


















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