var $ = {

    "params": {
        "target": 10,
        "x0": 0,
        "x1": 10,
        "error": 1e-6,
        "iteration": 0,
        "maxIteration": 1000
    },

    "secantMethod": function (func) {

        this.params.iteration = 0;

        var target = this.params.target;
        var error = this.params.error;
        var x0 = this.params.x0;
        var x1 = this.params.x1;

        while (Math.abs(x1 - x0) > error && this.params.iteration < this.params.maxIteration) {
            this.params.iteration += 1;

            var f0 = func(x0) - target;
            var f1 = func(x1) - target;

            if (Math.abs(f1 - f0) < error) {
                break;
            }

            var x2 = x1 - f1 * (x1 - x0) / (f1 - f0);

            x0 = x1;
            x1 = x2;
        }

        this.params.x0 = x0;
        this.params.x1 = x1;

        return x1;
    }
};

// Example Given

function testFunc(x) {
    return x*x ;
}

var result = $.secantMethod(testFunc);

var target = $.params.target;
var estimate = testFunc(result);
var error = target - estimate;

print("result :" + result);
print("estimate :" + estimate);
print("target :" + target);
print("error :" + error);
print("iteration :" + $.params.iteration);