#NumMeth Lab 4 (Newtons) COMPLETE

var eps = 0.001;

function f(x) { return x*x + x - 6; }
function df(x) { return 2*x + 1; }

function sgn(x) {
    if (x > 0) return 1;
    if (x < 0) return -1;
    return 0;
}

function newtons(fx, dfx, x0) {
    var x0, x1 = x0 - fx(x0)/dfx(x0);
    var steps = 0;

    while (true) {

        x0 = x1;
        x1 = x1 - fx(x1)/dfx(x1);

         if (0 == fx(x1))
            break;

        if (fx(x1) * fx(x1 + sgn(x0 - x1)*eps) < 0)
                break;

        steps++;
    }

    console.log("X=" + x1 + " steps=" + steps);
}

function lab4Main() {
    newtons(f, df, -7.5);
    //newtons(f, df, 7.5);
}