Polinómios de Lagrange

> PoliLagrange:=proc(X::vector,fX::vector,ind::nonnegint)
local i,j,L,n;
n:=vectdim(X);
L:=1.;
i:=ind+1;
for j from 1 to n do
if i<>j then
L:=L*(x-X[j])/(X[i]-X[j])
fi;
od;
RETURN(expand(L));
end:

> X:=vector(3,[2.2,2.4,2.6]);
fX:= vector(3,[0.520789,0.510423,0.481345]);

> L0:=PoliLagrange(X,fX,0);
L1:=PoliLagrange(X,fX,1);
L2:=PoliLagrange(X,fX,2);

> pol:=L0*fX[1]+L1*fX[2]+L2*fX[3];

> simplify(pol);