example_for_sean.sagews

L0(x) = (x-.6)*(x-.9)/(0.54)
L1(x) = x*(x - .9)/(-.18)
L2(x) = x*(x-.6)/(0.27)
P(x) = L0(x) + cos(0.6)*L1(x) + cos(0.9)*L2(x)
show(expand(P(x)))
P(0.45)

$\displaystyle -0.431086867014272 \, x^{2} - 0.0324551882753070 \, x + 1.00000000000000$

0.898100074705722