Please help !! Lagrange polynomial reconstruction

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polynomial reconstruction in matlab

Hi,

I am facing some difficulties with Matlab code for Lagrange polynomial reconstruction.

from the file do_lagranp.m attached:
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%do_lagranp.m
x = [1 2 3 4 5 6 7 8 9];

res = zeros(size(x));

for i = 1:9
res(i) = 512*x(i)^8 + 102*x(i)^7 + 1024*x(i)^6 + 806*x(i)^5 + ...
216*x(i)^4 + 117*x(i)^3 + 126*x(i)^2 + 132*x(i) + 41584;
end

y = res;

l = lagranp(x,y) %Find the lagrange polynomial
coef = round(l)

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If I were to use the x values as shown x = [1 2 3 4 5 6 7 8 9], then the code will have no problem in reconstructing the polynomial res by returning the exact coefficients [512 102 1024 806 216 117 .....]

But if I change the x values to something bigger, may be x = [100 200 300 ....],
then the code will not return the correct coefficients anymore.

Can someone please help me? Is there a maximum number that Matlab can only work on? What can I do to solve this issue because I really need the input for data x to be big value.

Thank you!!!