Differential of iterative function












0












$begingroup$


I previously got great help with understanding that



$$C = -Afrac{frac{K1}{f1^2H}+2frac{K1K2}{f1^2f2H^2}+3frac{K1K2K3}{f1^3f3H^3}}{1+frac{K1}{f1^2H}+frac{K1K2}{f1^2f2H^2}+frac{K1K2K3}{f1^3f3H^3}}$$



always had a positive differential in H (differentiation of difficult function with unknown constants)



Now I wonder if we can generalize - the general next entry in the numerator would be



$$ifrac{K1K2...Ki}{f1^ifiH^i}$$ and the next entry in the denominator would be



$$frac{K1K2...Ki}{f1^ifiH^i}$$ - it seems also from actual numeric experimenttion that it is indeed true that the general differential is still positive - but can we prove that?



I should add that all K and f values are positive and H (proton concentration) is also positive. K values are true thermodynamic constants, and f values, activity coefficients are assumed fixed for each value of total buffer concentration (A) as a first approximation.










share|cite|improve this question











$endgroup$

















    0












    $begingroup$


    I previously got great help with understanding that



    $$C = -Afrac{frac{K1}{f1^2H}+2frac{K1K2}{f1^2f2H^2}+3frac{K1K2K3}{f1^3f3H^3}}{1+frac{K1}{f1^2H}+frac{K1K2}{f1^2f2H^2}+frac{K1K2K3}{f1^3f3H^3}}$$



    always had a positive differential in H (differentiation of difficult function with unknown constants)



    Now I wonder if we can generalize - the general next entry in the numerator would be



    $$ifrac{K1K2...Ki}{f1^ifiH^i}$$ and the next entry in the denominator would be



    $$frac{K1K2...Ki}{f1^ifiH^i}$$ - it seems also from actual numeric experimenttion that it is indeed true that the general differential is still positive - but can we prove that?



    I should add that all K and f values are positive and H (proton concentration) is also positive. K values are true thermodynamic constants, and f values, activity coefficients are assumed fixed for each value of total buffer concentration (A) as a first approximation.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      I previously got great help with understanding that



      $$C = -Afrac{frac{K1}{f1^2H}+2frac{K1K2}{f1^2f2H^2}+3frac{K1K2K3}{f1^3f3H^3}}{1+frac{K1}{f1^2H}+frac{K1K2}{f1^2f2H^2}+frac{K1K2K3}{f1^3f3H^3}}$$



      always had a positive differential in H (differentiation of difficult function with unknown constants)



      Now I wonder if we can generalize - the general next entry in the numerator would be



      $$ifrac{K1K2...Ki}{f1^ifiH^i}$$ and the next entry in the denominator would be



      $$frac{K1K2...Ki}{f1^ifiH^i}$$ - it seems also from actual numeric experimenttion that it is indeed true that the general differential is still positive - but can we prove that?



      I should add that all K and f values are positive and H (proton concentration) is also positive. K values are true thermodynamic constants, and f values, activity coefficients are assumed fixed for each value of total buffer concentration (A) as a first approximation.










      share|cite|improve this question











      $endgroup$




      I previously got great help with understanding that



      $$C = -Afrac{frac{K1}{f1^2H}+2frac{K1K2}{f1^2f2H^2}+3frac{K1K2K3}{f1^3f3H^3}}{1+frac{K1}{f1^2H}+frac{K1K2}{f1^2f2H^2}+frac{K1K2K3}{f1^3f3H^3}}$$



      always had a positive differential in H (differentiation of difficult function with unknown constants)



      Now I wonder if we can generalize - the general next entry in the numerator would be



      $$ifrac{K1K2...Ki}{f1^ifiH^i}$$ and the next entry in the denominator would be



      $$frac{K1K2...Ki}{f1^ifiH^i}$$ - it seems also from actual numeric experimenttion that it is indeed true that the general differential is still positive - but can we prove that?



      I should add that all K and f values are positive and H (proton concentration) is also positive. K values are true thermodynamic constants, and f values, activity coefficients are assumed fixed for each value of total buffer concentration (A) as a first approximation.







      calculus






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 18 at 16:02







      user37217

















      asked Jan 14 at 8:39









      user37217user37217

      12




      12






















          1 Answer
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          active

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          0












          $begingroup$

          This is not a proof.



          Let $H=frac 1x$ and consider the function
          $$f=frac{sum _{i=1}^n i, a_i, x^i}{1+sum _{i=1}^n a_i, x^i}$$ Compute the derivative to get
          $$left(1+sum _{i=1}^n a_i, x^i right)^2, f'=left(sum _{i=1}^n i^2 a_i x^{i-1}right) left(1+sum _{i=1}^n a_i
          x^iright)-left(sum _{i=1}^n i a_i x^{i-1}right)left( sum _{i=1}^n i a_i
          x^iright)$$
          The rhs is then a polynomial of degree $2(n-1)$ that is to say



          $$text{rhs}=sum_{i=0}^{2(n-1)} b_i,x^i$$ in which the coefficients are all positive since all $a_i$'s are non negative. For example, using $n=10$, we should get
          $$left(
          begin{array}{cc}
          i & b_i \
          0 & a_1 \
          1 & 4 a_2 \
          2 & a_1 a_2+9 a_3 \
          3 & 4 a_1 a_3+16 a_4 \
          4 & a_2 a_3+9 a_1 a_4+25 a_5 \
          5 & 4 a_2 a_4+16 a_1 a_5+36 a_6 \
          6 & a_3 a_4+9 a_2 a_5+25 a_1 a_6+49 a_7 \
          7 & 4 a_3 a_5+16 a_2 a_6+36 a_1 a_7+64 a_8 \
          8 & a_4 a_5+9 a_3 a_6+25 a_2 a_7+49 a_1 a_8+81 a_9 \
          9 & 4 a_4 a_6+16 a_3 a_7+36 a_2 a_8+64 a_1 a_9+100 a_{10} \
          10 & a_5 a_6+9 a_4 a_7+25 a_3 a_8+49 a_2 a_9+81 a_1 a_{10} \
          11 & 4 a_5 a_7+16 a_4 a_8+36 a_3 a_9+64 a_2 a_{10} \
          12 & a_6 a_7+9 a_5 a_8+25 a_4 a_9+49 a_3 a_{10} \
          13 & 4 a_6 a_8+16 a_5 a_9+36 a_4 a_{10} \
          14 & a_7 a_8+9 a_6 a_9+25 a_5 a_{10} \
          15 & 4 a_7 a_9+16 a_6 a_{10} \
          16 & a_8 a_9+9 a_7 a_{10} \
          17 & 4 a_8 a_{10} \
          18 & a_9 a_{10}
          end{array}
          right)$$






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
            $endgroup$
            – user37217
            Jan 26 at 8:06










          • $begingroup$
            @user37217. You have sums of only positive terms.
            $endgroup$
            – Claude Leibovici
            Jan 26 at 8:43










          • $begingroup$
            Thanks a lot - so this is indeed a proof? - nice!!!
            $endgroup$
            – user37217
            Jan 26 at 13:35











          Your Answer





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          1 Answer
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          0












          $begingroup$

          This is not a proof.



          Let $H=frac 1x$ and consider the function
          $$f=frac{sum _{i=1}^n i, a_i, x^i}{1+sum _{i=1}^n a_i, x^i}$$ Compute the derivative to get
          $$left(1+sum _{i=1}^n a_i, x^i right)^2, f'=left(sum _{i=1}^n i^2 a_i x^{i-1}right) left(1+sum _{i=1}^n a_i
          x^iright)-left(sum _{i=1}^n i a_i x^{i-1}right)left( sum _{i=1}^n i a_i
          x^iright)$$
          The rhs is then a polynomial of degree $2(n-1)$ that is to say



          $$text{rhs}=sum_{i=0}^{2(n-1)} b_i,x^i$$ in which the coefficients are all positive since all $a_i$'s are non negative. For example, using $n=10$, we should get
          $$left(
          begin{array}{cc}
          i & b_i \
          0 & a_1 \
          1 & 4 a_2 \
          2 & a_1 a_2+9 a_3 \
          3 & 4 a_1 a_3+16 a_4 \
          4 & a_2 a_3+9 a_1 a_4+25 a_5 \
          5 & 4 a_2 a_4+16 a_1 a_5+36 a_6 \
          6 & a_3 a_4+9 a_2 a_5+25 a_1 a_6+49 a_7 \
          7 & 4 a_3 a_5+16 a_2 a_6+36 a_1 a_7+64 a_8 \
          8 & a_4 a_5+9 a_3 a_6+25 a_2 a_7+49 a_1 a_8+81 a_9 \
          9 & 4 a_4 a_6+16 a_3 a_7+36 a_2 a_8+64 a_1 a_9+100 a_{10} \
          10 & a_5 a_6+9 a_4 a_7+25 a_3 a_8+49 a_2 a_9+81 a_1 a_{10} \
          11 & 4 a_5 a_7+16 a_4 a_8+36 a_3 a_9+64 a_2 a_{10} \
          12 & a_6 a_7+9 a_5 a_8+25 a_4 a_9+49 a_3 a_{10} \
          13 & 4 a_6 a_8+16 a_5 a_9+36 a_4 a_{10} \
          14 & a_7 a_8+9 a_6 a_9+25 a_5 a_{10} \
          15 & 4 a_7 a_9+16 a_6 a_{10} \
          16 & a_8 a_9+9 a_7 a_{10} \
          17 & 4 a_8 a_{10} \
          18 & a_9 a_{10}
          end{array}
          right)$$






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
            $endgroup$
            – user37217
            Jan 26 at 8:06










          • $begingroup$
            @user37217. You have sums of only positive terms.
            $endgroup$
            – Claude Leibovici
            Jan 26 at 8:43










          • $begingroup$
            Thanks a lot - so this is indeed a proof? - nice!!!
            $endgroup$
            – user37217
            Jan 26 at 13:35
















          0












          $begingroup$

          This is not a proof.



          Let $H=frac 1x$ and consider the function
          $$f=frac{sum _{i=1}^n i, a_i, x^i}{1+sum _{i=1}^n a_i, x^i}$$ Compute the derivative to get
          $$left(1+sum _{i=1}^n a_i, x^i right)^2, f'=left(sum _{i=1}^n i^2 a_i x^{i-1}right) left(1+sum _{i=1}^n a_i
          x^iright)-left(sum _{i=1}^n i a_i x^{i-1}right)left( sum _{i=1}^n i a_i
          x^iright)$$
          The rhs is then a polynomial of degree $2(n-1)$ that is to say



          $$text{rhs}=sum_{i=0}^{2(n-1)} b_i,x^i$$ in which the coefficients are all positive since all $a_i$'s are non negative. For example, using $n=10$, we should get
          $$left(
          begin{array}{cc}
          i & b_i \
          0 & a_1 \
          1 & 4 a_2 \
          2 & a_1 a_2+9 a_3 \
          3 & 4 a_1 a_3+16 a_4 \
          4 & a_2 a_3+9 a_1 a_4+25 a_5 \
          5 & 4 a_2 a_4+16 a_1 a_5+36 a_6 \
          6 & a_3 a_4+9 a_2 a_5+25 a_1 a_6+49 a_7 \
          7 & 4 a_3 a_5+16 a_2 a_6+36 a_1 a_7+64 a_8 \
          8 & a_4 a_5+9 a_3 a_6+25 a_2 a_7+49 a_1 a_8+81 a_9 \
          9 & 4 a_4 a_6+16 a_3 a_7+36 a_2 a_8+64 a_1 a_9+100 a_{10} \
          10 & a_5 a_6+9 a_4 a_7+25 a_3 a_8+49 a_2 a_9+81 a_1 a_{10} \
          11 & 4 a_5 a_7+16 a_4 a_8+36 a_3 a_9+64 a_2 a_{10} \
          12 & a_6 a_7+9 a_5 a_8+25 a_4 a_9+49 a_3 a_{10} \
          13 & 4 a_6 a_8+16 a_5 a_9+36 a_4 a_{10} \
          14 & a_7 a_8+9 a_6 a_9+25 a_5 a_{10} \
          15 & 4 a_7 a_9+16 a_6 a_{10} \
          16 & a_8 a_9+9 a_7 a_{10} \
          17 & 4 a_8 a_{10} \
          18 & a_9 a_{10}
          end{array}
          right)$$






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
            $endgroup$
            – user37217
            Jan 26 at 8:06










          • $begingroup$
            @user37217. You have sums of only positive terms.
            $endgroup$
            – Claude Leibovici
            Jan 26 at 8:43










          • $begingroup$
            Thanks a lot - so this is indeed a proof? - nice!!!
            $endgroup$
            – user37217
            Jan 26 at 13:35














          0












          0








          0





          $begingroup$

          This is not a proof.



          Let $H=frac 1x$ and consider the function
          $$f=frac{sum _{i=1}^n i, a_i, x^i}{1+sum _{i=1}^n a_i, x^i}$$ Compute the derivative to get
          $$left(1+sum _{i=1}^n a_i, x^i right)^2, f'=left(sum _{i=1}^n i^2 a_i x^{i-1}right) left(1+sum _{i=1}^n a_i
          x^iright)-left(sum _{i=1}^n i a_i x^{i-1}right)left( sum _{i=1}^n i a_i
          x^iright)$$
          The rhs is then a polynomial of degree $2(n-1)$ that is to say



          $$text{rhs}=sum_{i=0}^{2(n-1)} b_i,x^i$$ in which the coefficients are all positive since all $a_i$'s are non negative. For example, using $n=10$, we should get
          $$left(
          begin{array}{cc}
          i & b_i \
          0 & a_1 \
          1 & 4 a_2 \
          2 & a_1 a_2+9 a_3 \
          3 & 4 a_1 a_3+16 a_4 \
          4 & a_2 a_3+9 a_1 a_4+25 a_5 \
          5 & 4 a_2 a_4+16 a_1 a_5+36 a_6 \
          6 & a_3 a_4+9 a_2 a_5+25 a_1 a_6+49 a_7 \
          7 & 4 a_3 a_5+16 a_2 a_6+36 a_1 a_7+64 a_8 \
          8 & a_4 a_5+9 a_3 a_6+25 a_2 a_7+49 a_1 a_8+81 a_9 \
          9 & 4 a_4 a_6+16 a_3 a_7+36 a_2 a_8+64 a_1 a_9+100 a_{10} \
          10 & a_5 a_6+9 a_4 a_7+25 a_3 a_8+49 a_2 a_9+81 a_1 a_{10} \
          11 & 4 a_5 a_7+16 a_4 a_8+36 a_3 a_9+64 a_2 a_{10} \
          12 & a_6 a_7+9 a_5 a_8+25 a_4 a_9+49 a_3 a_{10} \
          13 & 4 a_6 a_8+16 a_5 a_9+36 a_4 a_{10} \
          14 & a_7 a_8+9 a_6 a_9+25 a_5 a_{10} \
          15 & 4 a_7 a_9+16 a_6 a_{10} \
          16 & a_8 a_9+9 a_7 a_{10} \
          17 & 4 a_8 a_{10} \
          18 & a_9 a_{10}
          end{array}
          right)$$






          share|cite|improve this answer









          $endgroup$



          This is not a proof.



          Let $H=frac 1x$ and consider the function
          $$f=frac{sum _{i=1}^n i, a_i, x^i}{1+sum _{i=1}^n a_i, x^i}$$ Compute the derivative to get
          $$left(1+sum _{i=1}^n a_i, x^i right)^2, f'=left(sum _{i=1}^n i^2 a_i x^{i-1}right) left(1+sum _{i=1}^n a_i
          x^iright)-left(sum _{i=1}^n i a_i x^{i-1}right)left( sum _{i=1}^n i a_i
          x^iright)$$
          The rhs is then a polynomial of degree $2(n-1)$ that is to say



          $$text{rhs}=sum_{i=0}^{2(n-1)} b_i,x^i$$ in which the coefficients are all positive since all $a_i$'s are non negative. For example, using $n=10$, we should get
          $$left(
          begin{array}{cc}
          i & b_i \
          0 & a_1 \
          1 & 4 a_2 \
          2 & a_1 a_2+9 a_3 \
          3 & 4 a_1 a_3+16 a_4 \
          4 & a_2 a_3+9 a_1 a_4+25 a_5 \
          5 & 4 a_2 a_4+16 a_1 a_5+36 a_6 \
          6 & a_3 a_4+9 a_2 a_5+25 a_1 a_6+49 a_7 \
          7 & 4 a_3 a_5+16 a_2 a_6+36 a_1 a_7+64 a_8 \
          8 & a_4 a_5+9 a_3 a_6+25 a_2 a_7+49 a_1 a_8+81 a_9 \
          9 & 4 a_4 a_6+16 a_3 a_7+36 a_2 a_8+64 a_1 a_9+100 a_{10} \
          10 & a_5 a_6+9 a_4 a_7+25 a_3 a_8+49 a_2 a_9+81 a_1 a_{10} \
          11 & 4 a_5 a_7+16 a_4 a_8+36 a_3 a_9+64 a_2 a_{10} \
          12 & a_6 a_7+9 a_5 a_8+25 a_4 a_9+49 a_3 a_{10} \
          13 & 4 a_6 a_8+16 a_5 a_9+36 a_4 a_{10} \
          14 & a_7 a_8+9 a_6 a_9+25 a_5 a_{10} \
          15 & 4 a_7 a_9+16 a_6 a_{10} \
          16 & a_8 a_9+9 a_7 a_{10} \
          17 & 4 a_8 a_{10} \
          18 & a_9 a_{10}
          end{array}
          right)$$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 22 at 13:00









          Claude LeiboviciClaude Leibovici

          124k1158135




          124k1158135












          • $begingroup$
            Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
            $endgroup$
            – user37217
            Jan 26 at 8:06










          • $begingroup$
            @user37217. You have sums of only positive terms.
            $endgroup$
            – Claude Leibovici
            Jan 26 at 8:43










          • $begingroup$
            Thanks a lot - so this is indeed a proof? - nice!!!
            $endgroup$
            – user37217
            Jan 26 at 13:35


















          • $begingroup$
            Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
            $endgroup$
            – user37217
            Jan 26 at 8:06










          • $begingroup$
            @user37217. You have sums of only positive terms.
            $endgroup$
            – Claude Leibovici
            Jan 26 at 8:43










          • $begingroup$
            Thanks a lot - so this is indeed a proof? - nice!!!
            $endgroup$
            – user37217
            Jan 26 at 13:35
















          $begingroup$
          Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
          $endgroup$
          – user37217
          Jan 26 at 8:06




          $begingroup$
          Thanks a lot - but what is then the interpretation in regard tothe question of whether we caan know if thederivativeis positive?
          $endgroup$
          – user37217
          Jan 26 at 8:06












          $begingroup$
          @user37217. You have sums of only positive terms.
          $endgroup$
          – Claude Leibovici
          Jan 26 at 8:43




          $begingroup$
          @user37217. You have sums of only positive terms.
          $endgroup$
          – Claude Leibovici
          Jan 26 at 8:43












          $begingroup$
          Thanks a lot - so this is indeed a proof? - nice!!!
          $endgroup$
          – user37217
          Jan 26 at 13:35




          $begingroup$
          Thanks a lot - so this is indeed a proof? - nice!!!
          $endgroup$
          – user37217
          Jan 26 at 13:35


















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