Rational Polynomial Interpolation
Pari/GP, 14 bytes

polinterpolate


Takes two lists [x1, ..., xn] and [y1, ..., yn] as input. Outputs a polynomial.

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Pari/GP, 37 bytes, without built-in

f(x,y)=y/matrix(#x,#x,i,j,x[j]^(i-1))


Takes two lists [x1, ..., xn] and [y1, ..., yn] as input. Outputs a list of coefficients.

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