extremal problem-how to check istrong minima,maxima condition












1














The functional $I[y(x)]=int_{0}^{2}(xy^{'}+y^{'2})dx$,y(0)=1,y(2)=0
possess



a.strong minima



b.strong maxima



c.strong maxima but not weak minima



d.weak maxima but not strong minima



How do we show if the functiona is strong minima,maxima..how do we prove this?
what all we have to check?










share|cite|improve this question



























    1














    The functional $I[y(x)]=int_{0}^{2}(xy^{'}+y^{'2})dx$,y(0)=1,y(2)=0
    possess



    a.strong minima



    b.strong maxima



    c.strong maxima but not weak minima



    d.weak maxima but not strong minima



    How do we show if the functiona is strong minima,maxima..how do we prove this?
    what all we have to check?










    share|cite|improve this question

























      1












      1








      1


      1





      The functional $I[y(x)]=int_{0}^{2}(xy^{'}+y^{'2})dx$,y(0)=1,y(2)=0
      possess



      a.strong minima



      b.strong maxima



      c.strong maxima but not weak minima



      d.weak maxima but not strong minima



      How do we show if the functiona is strong minima,maxima..how do we prove this?
      what all we have to check?










      share|cite|improve this question













      The functional $I[y(x)]=int_{0}^{2}(xy^{'}+y^{'2})dx$,y(0)=1,y(2)=0
      possess



      a.strong minima



      b.strong maxima



      c.strong maxima but not weak minima



      d.weak maxima but not strong minima



      How do we show if the functiona is strong minima,maxima..how do we prove this?
      what all we have to check?







      calculus-of-variations






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Sep 1 '14 at 10:04









      amit

      107312




      107312






















          1 Answer
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          0














          It has Strong minima.



          Legendre Condition: $F_{y'y'}$ (differentiate F w.r.t y' twice) >0 for every y then strong minima and if$ F_{y'y'}<0$ for every y' then Strong maxima.



          for >0 for some y' close to p=(dy/dx, y is extremal) weak minima and for <0 for some y' close to p=(dy/dx, y is extremal) weak maxima






          share|cite|improve this answer



















          • 1




            @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
            – happymath
            Jan 23 '15 at 9:52










          • In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
            – user3057692
            Mar 14 '15 at 16:10











          Your Answer





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          1 Answer
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          1 Answer
          1






          active

          oldest

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          active

          oldest

          votes






          active

          oldest

          votes









          0














          It has Strong minima.



          Legendre Condition: $F_{y'y'}$ (differentiate F w.r.t y' twice) >0 for every y then strong minima and if$ F_{y'y'}<0$ for every y' then Strong maxima.



          for >0 for some y' close to p=(dy/dx, y is extremal) weak minima and for <0 for some y' close to p=(dy/dx, y is extremal) weak maxima






          share|cite|improve this answer



















          • 1




            @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
            – happymath
            Jan 23 '15 at 9:52










          • In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
            – user3057692
            Mar 14 '15 at 16:10
















          0














          It has Strong minima.



          Legendre Condition: $F_{y'y'}$ (differentiate F w.r.t y' twice) >0 for every y then strong minima and if$ F_{y'y'}<0$ for every y' then Strong maxima.



          for >0 for some y' close to p=(dy/dx, y is extremal) weak minima and for <0 for some y' close to p=(dy/dx, y is extremal) weak maxima






          share|cite|improve this answer



















          • 1




            @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
            – happymath
            Jan 23 '15 at 9:52










          • In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
            – user3057692
            Mar 14 '15 at 16:10














          0












          0








          0






          It has Strong minima.



          Legendre Condition: $F_{y'y'}$ (differentiate F w.r.t y' twice) >0 for every y then strong minima and if$ F_{y'y'}<0$ for every y' then Strong maxima.



          for >0 for some y' close to p=(dy/dx, y is extremal) weak minima and for <0 for some y' close to p=(dy/dx, y is extremal) weak maxima






          share|cite|improve this answer














          It has Strong minima.



          Legendre Condition: $F_{y'y'}$ (differentiate F w.r.t y' twice) >0 for every y then strong minima and if$ F_{y'y'}<0$ for every y' then Strong maxima.



          for >0 for some y' close to p=(dy/dx, y is extremal) weak minima and for <0 for some y' close to p=(dy/dx, y is extremal) weak maxima







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 29 '15 at 9:12

























          answered Jan 23 '15 at 9:34









          user3057692

          11




          11








          • 1




            @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
            – happymath
            Jan 23 '15 at 9:52










          • In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
            – user3057692
            Mar 14 '15 at 16:10














          • 1




            @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
            – happymath
            Jan 23 '15 at 9:52










          • In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
            – user3057692
            Mar 14 '15 at 16:10








          1




          1




          @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
          – happymath
          Jan 23 '15 at 9:52




          @user30567692 I tried to edit your answer but the I could not understand the second half please try to use LATEX
          – happymath
          Jan 23 '15 at 9:52












          In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
          – user3057692
          Mar 14 '15 at 16:10




          In your example, Fy'y' = 2>0 for every y'. Therefore it is strong minima. Let us assume thet for some problem your Fy'y' = y'+x, Now its sign is not clear and it depend on sign of p=dy/dx (where y is extremal) and range of x, So it is definitaley week ( maxima or minima will depend on sign)
          – user3057692
          Mar 14 '15 at 16:10


















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