How to calculate the value of polynomial value for 150 coefficient.It is not possible to use polyval function.

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YOGESHWARI PATEL 2016-12-25

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https://ww2.mathworks.cn/matlabcentral/answers/318124-how-to-calculate-the-value-of-polynomial-value-for-150-coefficient-it-is-not-possible-to-use-polyval

评论： Walter Roberson 2016-12-26

I try this

 for k=1:150
    x=x1(k);   
   fprintf('============')
      sum1=0;
    b=0;
   for i=1:2     
         b=b+B1(i)*power(x,i) ;
         sum1=sum1+b;  
        end
  final(i)=10000+sum1;  
 end

回答（1 个）

Walter Roberson 2016-12-25

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https://ww2.mathworks.cn/matlabcentral/answers/318124-how-to-calculate-the-value-of-polynomial-value-for-150-coefficient-it-is-not-possible-to-use-polyval#answer_248426

在 MATLAB Online 中打开

final = 10000 + B1(1) * x1(1:150) + B1(2) * x1(1:150).^2 ;

This can be written as

final = 10000 + B1(1) * x1 + B1(2) * x1.^2 ;

if x1 is exactly 150 items long.

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John D'Errico 2016-12-25

编辑：John D'Errico 2016-12-25

It will "work". It will produce complete garbage. But that is a completely different issue, as you well know.

Walter Roberson 2016-12-26

Yep. And unless the user happens to have pure integer coefficients and pure integer x values, it is not clear that they could meaningfully get anything other than garbage (at least not with less than 1800 decimal places results.)

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