Linear approximation to xln(x)












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Suppose we need to approximate $f(8.4)$ where $f(x) = mathbb{xln(x)}$ by using a linear polynomial . We have the following points as nodes : $x_0=8.1 , x_1 = 8.3 , x_2 = 8.6 , x_3 = 8.7$ .



I realize that we can use Lagrange Interpolation to fit a linear polynomial by choosing any two nodal points . But , as I have been given $4$ nodal points , how should I choose the best two points for the approximation (without evaluating $f$ directly at $x = 8.4$ ) ?










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    $begingroup$


    Suppose we need to approximate $f(8.4)$ where $f(x) = mathbb{xln(x)}$ by using a linear polynomial . We have the following points as nodes : $x_0=8.1 , x_1 = 8.3 , x_2 = 8.6 , x_3 = 8.7$ .



    I realize that we can use Lagrange Interpolation to fit a linear polynomial by choosing any two nodal points . But , as I have been given $4$ nodal points , how should I choose the best two points for the approximation (without evaluating $f$ directly at $x = 8.4$ ) ?










    share|cite|improve this question









    $endgroup$















      1












      1








      1


      1



      $begingroup$


      Suppose we need to approximate $f(8.4)$ where $f(x) = mathbb{xln(x)}$ by using a linear polynomial . We have the following points as nodes : $x_0=8.1 , x_1 = 8.3 , x_2 = 8.6 , x_3 = 8.7$ .



      I realize that we can use Lagrange Interpolation to fit a linear polynomial by choosing any two nodal points . But , as I have been given $4$ nodal points , how should I choose the best two points for the approximation (without evaluating $f$ directly at $x = 8.4$ ) ?










      share|cite|improve this question









      $endgroup$




      Suppose we need to approximate $f(8.4)$ where $f(x) = mathbb{xln(x)}$ by using a linear polynomial . We have the following points as nodes : $x_0=8.1 , x_1 = 8.3 , x_2 = 8.6 , x_3 = 8.7$ .



      I realize that we can use Lagrange Interpolation to fit a linear polynomial by choosing any two nodal points . But , as I have been given $4$ nodal points , how should I choose the best two points for the approximation (without evaluating $f$ directly at $x = 8.4$ ) ?







      numerical-methods numerical-optimization lagrange-interpolation






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      asked Feb 3 at 5:11









      JohnJohn

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      363113






















          2 Answers
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          1












          $begingroup$

          I would use a piecewise linear function, making a linear function between each pair of points. As $8.4$ is between $8.3$ and $8.6$, use those two points.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
            $endgroup$
            – John
            Feb 3 at 5:28






          • 1




            $begingroup$
            You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
            $endgroup$
            – Ross Millikan
            Feb 3 at 5:33










          • $begingroup$
            Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
            $endgroup$
            – John
            Feb 3 at 5:39






          • 1




            $begingroup$
            Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
            $endgroup$
            – Ross Millikan
            Feb 4 at 14:06



















          2












          $begingroup$

          What I would do is to consider
          $$Phi=int_{8.1}^{8.7} (x log(x)-a-bx)^2 ,dx$$ which is equivalent to a linear regression with an infinite number of data points.



          Use the fact that, expanding and using integrations by parts
          $$I=int (x log(x)-a-bx)^2 ,dx$$ $$I=frac{1}{54} x left(54 a^2+27 a (2 b x+x)-6 x log (x) (9 a+6 b x+2 x)+2 left(9
          b^2+6 b+2right) x^2+18 x^2 log ^2(x)right)$$
          Use the bounds to get
          $$Phi=0.6 a^2+a (10.08 b-21.4547)+42.354 b^2-180.332 b+191.97$$ Compute the partial derivatives and set them equal to $0$; this gives two equations for two unknowns $(a,b)$ and the solution would be ${a= -8.39714,b= 3.12810}$.



          Then, for $x=8.4$, you will get $17.8789$ while the exact value is $17.8771$.



          Edit



          Using exact arithmetic, it is possible to compute the exact values of parameters $a$ and $b$ using the classical least square method for the four data points as well as for the integration. The formulae will not be reported here (too messy); for sure, they are not very different $(0.008text{%})$. However
          $$frac{Phi_{ols}}{Phi_{int}}=2.0414$$






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
            $endgroup$
            – John
            Feb 3 at 6:19






          • 1




            $begingroup$
            @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
            $endgroup$
            – Claude Leibovici
            Feb 3 at 6:44










          • $begingroup$
            Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
            $endgroup$
            – John
            Feb 3 at 7:01






          • 1




            $begingroup$
            @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
            $endgroup$
            – Claude Leibovici
            Feb 3 at 7:29












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          2 Answers
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          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1












          $begingroup$

          I would use a piecewise linear function, making a linear function between each pair of points. As $8.4$ is between $8.3$ and $8.6$, use those two points.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
            $endgroup$
            – John
            Feb 3 at 5:28






          • 1




            $begingroup$
            You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
            $endgroup$
            – Ross Millikan
            Feb 3 at 5:33










          • $begingroup$
            Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
            $endgroup$
            – John
            Feb 3 at 5:39






          • 1




            $begingroup$
            Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
            $endgroup$
            – Ross Millikan
            Feb 4 at 14:06
















          1












          $begingroup$

          I would use a piecewise linear function, making a linear function between each pair of points. As $8.4$ is between $8.3$ and $8.6$, use those two points.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
            $endgroup$
            – John
            Feb 3 at 5:28






          • 1




            $begingroup$
            You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
            $endgroup$
            – Ross Millikan
            Feb 3 at 5:33










          • $begingroup$
            Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
            $endgroup$
            – John
            Feb 3 at 5:39






          • 1




            $begingroup$
            Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
            $endgroup$
            – Ross Millikan
            Feb 4 at 14:06














          1












          1








          1





          $begingroup$

          I would use a piecewise linear function, making a linear function between each pair of points. As $8.4$ is between $8.3$ and $8.6$, use those two points.






          share|cite|improve this answer









          $endgroup$



          I would use a piecewise linear function, making a linear function between each pair of points. As $8.4$ is between $8.3$ and $8.6$, use those two points.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Feb 3 at 5:22









          Ross MillikanRoss Millikan

          301k24200375




          301k24200375












          • $begingroup$
            I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
            $endgroup$
            – John
            Feb 3 at 5:28






          • 1




            $begingroup$
            You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
            $endgroup$
            – Ross Millikan
            Feb 3 at 5:33










          • $begingroup$
            Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
            $endgroup$
            – John
            Feb 3 at 5:39






          • 1




            $begingroup$
            Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
            $endgroup$
            – Ross Millikan
            Feb 4 at 14:06


















          • $begingroup$
            I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
            $endgroup$
            – John
            Feb 3 at 5:28






          • 1




            $begingroup$
            You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
            $endgroup$
            – Ross Millikan
            Feb 3 at 5:33










          • $begingroup$
            Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
            $endgroup$
            – John
            Feb 3 at 5:39






          • 1




            $begingroup$
            Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
            $endgroup$
            – Ross Millikan
            Feb 4 at 14:06
















          $begingroup$
          I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
          $endgroup$
          – John
          Feb 3 at 5:28




          $begingroup$
          I am aware of the fact that piecewise linear function can be used , but our driving force should be to minimize the error in finding f at 8.4 , isn't it ? (Please correct me if I am saying something wrong ) . So , basically if we know f at two nodal points then , we cannot extract more information about f(8.4) from the other two nodal points that we have not used ?
          $endgroup$
          – John
          Feb 3 at 5:28




          1




          1




          $begingroup$
          You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
          $endgroup$
          – Ross Millikan
          Feb 3 at 5:33




          $begingroup$
          You can't with a linear function. For a linear function you are best served by using the two closest points. If you had data at $8.0,8.3,9.0$ you could argue you should use the $8.0,8.3$ data, but it is also attractive to use bracketing points. Extracting information from other points corresponds to using a higher order interpolation. That is a fine idea, but your question prohibits it.
          $endgroup$
          – Ross Millikan
          Feb 3 at 5:33












          $begingroup$
          Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
          $endgroup$
          – John
          Feb 3 at 5:39




          $begingroup$
          Thank you so much ! Also , what are 'bracketing points' ? I haven't heard of it before !
          $endgroup$
          – John
          Feb 3 at 5:39




          1




          1




          $begingroup$
          Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
          $endgroup$
          – Ross Millikan
          Feb 4 at 14:06




          $begingroup$
          Bracketing points are ones on opposite sides of the point of interest. For interpolation, they are usually the ones next to the point of interest. For 1D root finding they are points where the function is known to have opposite signs, meaning (assuming it is continuous) there is a root somewhere in between.
          $endgroup$
          – Ross Millikan
          Feb 4 at 14:06











          2












          $begingroup$

          What I would do is to consider
          $$Phi=int_{8.1}^{8.7} (x log(x)-a-bx)^2 ,dx$$ which is equivalent to a linear regression with an infinite number of data points.



          Use the fact that, expanding and using integrations by parts
          $$I=int (x log(x)-a-bx)^2 ,dx$$ $$I=frac{1}{54} x left(54 a^2+27 a (2 b x+x)-6 x log (x) (9 a+6 b x+2 x)+2 left(9
          b^2+6 b+2right) x^2+18 x^2 log ^2(x)right)$$
          Use the bounds to get
          $$Phi=0.6 a^2+a (10.08 b-21.4547)+42.354 b^2-180.332 b+191.97$$ Compute the partial derivatives and set them equal to $0$; this gives two equations for two unknowns $(a,b)$ and the solution would be ${a= -8.39714,b= 3.12810}$.



          Then, for $x=8.4$, you will get $17.8789$ while the exact value is $17.8771$.



          Edit



          Using exact arithmetic, it is possible to compute the exact values of parameters $a$ and $b$ using the classical least square method for the four data points as well as for the integration. The formulae will not be reported here (too messy); for sure, they are not very different $(0.008text{%})$. However
          $$frac{Phi_{ols}}{Phi_{int}}=2.0414$$






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
            $endgroup$
            – John
            Feb 3 at 6:19






          • 1




            $begingroup$
            @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
            $endgroup$
            – Claude Leibovici
            Feb 3 at 6:44










          • $begingroup$
            Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
            $endgroup$
            – John
            Feb 3 at 7:01






          • 1




            $begingroup$
            @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
            $endgroup$
            – Claude Leibovici
            Feb 3 at 7:29
















          2












          $begingroup$

          What I would do is to consider
          $$Phi=int_{8.1}^{8.7} (x log(x)-a-bx)^2 ,dx$$ which is equivalent to a linear regression with an infinite number of data points.



          Use the fact that, expanding and using integrations by parts
          $$I=int (x log(x)-a-bx)^2 ,dx$$ $$I=frac{1}{54} x left(54 a^2+27 a (2 b x+x)-6 x log (x) (9 a+6 b x+2 x)+2 left(9
          b^2+6 b+2right) x^2+18 x^2 log ^2(x)right)$$
          Use the bounds to get
          $$Phi=0.6 a^2+a (10.08 b-21.4547)+42.354 b^2-180.332 b+191.97$$ Compute the partial derivatives and set them equal to $0$; this gives two equations for two unknowns $(a,b)$ and the solution would be ${a= -8.39714,b= 3.12810}$.



          Then, for $x=8.4$, you will get $17.8789$ while the exact value is $17.8771$.



          Edit



          Using exact arithmetic, it is possible to compute the exact values of parameters $a$ and $b$ using the classical least square method for the four data points as well as for the integration. The formulae will not be reported here (too messy); for sure, they are not very different $(0.008text{%})$. However
          $$frac{Phi_{ols}}{Phi_{int}}=2.0414$$






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
            $endgroup$
            – John
            Feb 3 at 6:19






          • 1




            $begingroup$
            @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
            $endgroup$
            – Claude Leibovici
            Feb 3 at 6:44










          • $begingroup$
            Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
            $endgroup$
            – John
            Feb 3 at 7:01






          • 1




            $begingroup$
            @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
            $endgroup$
            – Claude Leibovici
            Feb 3 at 7:29














          2












          2








          2





          $begingroup$

          What I would do is to consider
          $$Phi=int_{8.1}^{8.7} (x log(x)-a-bx)^2 ,dx$$ which is equivalent to a linear regression with an infinite number of data points.



          Use the fact that, expanding and using integrations by parts
          $$I=int (x log(x)-a-bx)^2 ,dx$$ $$I=frac{1}{54} x left(54 a^2+27 a (2 b x+x)-6 x log (x) (9 a+6 b x+2 x)+2 left(9
          b^2+6 b+2right) x^2+18 x^2 log ^2(x)right)$$
          Use the bounds to get
          $$Phi=0.6 a^2+a (10.08 b-21.4547)+42.354 b^2-180.332 b+191.97$$ Compute the partial derivatives and set them equal to $0$; this gives two equations for two unknowns $(a,b)$ and the solution would be ${a= -8.39714,b= 3.12810}$.



          Then, for $x=8.4$, you will get $17.8789$ while the exact value is $17.8771$.



          Edit



          Using exact arithmetic, it is possible to compute the exact values of parameters $a$ and $b$ using the classical least square method for the four data points as well as for the integration. The formulae will not be reported here (too messy); for sure, they are not very different $(0.008text{%})$. However
          $$frac{Phi_{ols}}{Phi_{int}}=2.0414$$






          share|cite|improve this answer











          $endgroup$



          What I would do is to consider
          $$Phi=int_{8.1}^{8.7} (x log(x)-a-bx)^2 ,dx$$ which is equivalent to a linear regression with an infinite number of data points.



          Use the fact that, expanding and using integrations by parts
          $$I=int (x log(x)-a-bx)^2 ,dx$$ $$I=frac{1}{54} x left(54 a^2+27 a (2 b x+x)-6 x log (x) (9 a+6 b x+2 x)+2 left(9
          b^2+6 b+2right) x^2+18 x^2 log ^2(x)right)$$
          Use the bounds to get
          $$Phi=0.6 a^2+a (10.08 b-21.4547)+42.354 b^2-180.332 b+191.97$$ Compute the partial derivatives and set them equal to $0$; this gives two equations for two unknowns $(a,b)$ and the solution would be ${a= -8.39714,b= 3.12810}$.



          Then, for $x=8.4$, you will get $17.8789$ while the exact value is $17.8771$.



          Edit



          Using exact arithmetic, it is possible to compute the exact values of parameters $a$ and $b$ using the classical least square method for the four data points as well as for the integration. The formulae will not be reported here (too messy); for sure, they are not very different $(0.008text{%})$. However
          $$frac{Phi_{ols}}{Phi_{int}}=2.0414$$







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Feb 3 at 14:23

























          answered Feb 3 at 6:02









          Claude LeiboviciClaude Leibovici

          126k1158135




          126k1158135












          • $begingroup$
            Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
            $endgroup$
            – John
            Feb 3 at 6:19






          • 1




            $begingroup$
            @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
            $endgroup$
            – Claude Leibovici
            Feb 3 at 6:44










          • $begingroup$
            Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
            $endgroup$
            – John
            Feb 3 at 7:01






          • 1




            $begingroup$
            @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
            $endgroup$
            – Claude Leibovici
            Feb 3 at 7:29


















          • $begingroup$
            Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
            $endgroup$
            – John
            Feb 3 at 6:19






          • 1




            $begingroup$
            @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
            $endgroup$
            – Claude Leibovici
            Feb 3 at 6:44










          • $begingroup$
            Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
            $endgroup$
            – John
            Feb 3 at 7:01






          • 1




            $begingroup$
            @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
            $endgroup$
            – Claude Leibovici
            Feb 3 at 7:29
















          $begingroup$
          Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
          $endgroup$
          – John
          Feb 3 at 6:19




          $begingroup$
          Never thought it this way ! Can you please suggest some reading on this approach . But , note that that linear approximation yields $17.87833$ which is actually a bit more accurate than this method .
          $endgroup$
          – John
          Feb 3 at 6:19




          1




          1




          $begingroup$
          @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
          $endgroup$
          – Claude Leibovici
          Feb 3 at 6:44




          $begingroup$
          @John. As I wrote, this is equivalent to the linear regression with an infinite number of data points. Then, the summation is transformed to an integral. Think about it and you will see that it is simple. The result is the best fit over the entire range of $x$.
          $endgroup$
          – Claude Leibovici
          Feb 3 at 6:44












          $begingroup$
          Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
          $endgroup$
          – John
          Feb 3 at 7:01




          $begingroup$
          Yes, you are correct ! I am still a novice learner , so I could not appreciate this fact earlier . Thanks a lot ! :)
          $endgroup$
          – John
          Feb 3 at 7:01




          1




          1




          $begingroup$
          @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
          $endgroup$
          – Claude Leibovici
          Feb 3 at 7:29




          $begingroup$
          @John. Almost every single day, I am still a novice learner too. This is the beauty of mathematics; it is a so vaste domain !
          $endgroup$
          – Claude Leibovici
          Feb 3 at 7:29


















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