import mir.math.common: approxEqual;

double[] x = [3.0, 4.5, 1.9, 2];

alias   f = (x) =>     3.0 +     4.5 * x^^1 +   1.9 * x^^2 + 2 * x^^3;
alias  df = (x) =>     4.5 + 2 * 1.9 * x^^1 + 3 * 2 * x^^2;
alias d2f = (x) => 2 * 1.9 + 6 *   2 * x^^1;

assert(poly(3.3, x).approxEqual(f(3.3)));
assert(poly(7.2, x).approxEqual(f(7.2)));

assert(poly!1(3.3, x).approxEqual(df(3.3)));
assert(poly!1(7.2, x).approxEqual(df(7.2)));

assert(poly!2(3.3, x).approxEqual(d2f(3.3)));
assert(poly!2(7.2, x).approxEqual(d2f(7.2)));