export var trid = {
    'f' : function(X) {
        var x = X[0], y = X[1];
        return (x - 1) * (x - 1) + (y - 1) * (y - 1) - x * y;
    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 2 * (x - 1) - y;
        fxprime[1] = 2* (y - 1) - x;
        return fxprime;
    },

    'xDomain': [-4, 4],
    'yDomain': [4, -4]
};

export var dixonPrice = {
    'f' : function(X) {
        var x = X[0], y = X[1];

        return (x - 1) * (x - 1)  + 2 * ( 2 * y - x) * ( 2 * y - x);
    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 2 * (x - 1) - 2 * (2 * y - x);
        fxprime[1] = 4 * (2 * y - x);
        return fxprime;
    },

    'xDomain': [-10, 10],
    'yDomain': [10, -10]
};

export var banana = {
    'initial': [-1, -1],
    'f' : function(X) {
        var x = X[0], y = X[1];
        return (1 - x) * (1 - x) + 100 * (y - x * x) * (y - x * x);
    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 400 * x * x * x - 400 * y * x + 2 * x - 2;
        fxprime[1] = 200 * y - 200 * x * x;
        return fxprime;
    },

    'xDomain': [-2, 2],
    'yDomain': [2, -2]
};

export var matyas = {
    'initial': [-9.08, -7.83],

    'f' : function(X) {
        var x = X[0], y = X[1];
        return 0.26 * (x * x + y * y)  - 0.48 * x * y;

    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 0.52 * x - 0.48 * y;
        fxprime[1] = 0.52 * y - 0.48 * x;
        return fxprime;
    },

    'xDomain': [-10, 10],
    'yDomain': [10, -10]
};

export var booth = {
    'f' : function(X) {
        var x = X[0], y = X[1];
        return Math.pow(x + 2 * y - 7, 2) + Math.pow(2 * x + y - 5, 2);
    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 2 * (x + 2 *y  - 7) + 4 * (2 * x + y - 5);
        fxprime[1] = 4 * (x + 2 * y - 7) + 2 * (2 * x + y - 5);
        return fxprime;
    },

    'xDomain': [-10, 10],
    'yDomain': [10, -10]
};

export var himmelblau = {
    'initial': [-0.15, 0.67],
    'f': function(X) {
        var x = X[0], y = X[1];
        return (x * x + y - 11) * ( x * x + y - 11) + (x + y * y - 7) * (x + y * y - 7);
    },
    'fprime': function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = 4 * (x * x + y - 11) * x + 2 * (x + y * y - 7);
        fxprime[1] = 2 * (x * x + y - 11)  + 4 * (x + y * y - 7) * y;
        return fxprime;
    },
    'xDomain': [-6.1, 6],
    'yDomain': [6, -6],
    'minima' : [{x : 3.584428, y : -1.848126},
             {x : -2.805118, y : 3.131312},
             {x : -3.779310, y : -3.283186},
             {x : 3, y : 2}],
    'colourDomain' : [2, 13]
};

export var flower = {
    'initial': [-3.5, 3.5],

    'f': function(X) {
        var x = X[0], y = X[1];
        return Math.sin(y) * x  + Math.sin(x) * y  +  x * x +  y *y;
    },

    'fprime': function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = Math.sin(y) + Math.cos(x) * y + 2 * x;
        fxprime[1] = Math.sin(x) + Math.cos(y) * x + 2 * y;
        return fxprime;
    },

    'xDomain': [-6, 6],
    'yDomain': [6, -6]
};

export var mccormick = {
    'f' : function(X) {
        var x = X[0], y = X[1];
            return Math.sin(x + y) + (x - y) * (x -y) - 1.5 * x + 2.5 * y + 3;
    },

    'fprime' : function(X, fxprime) {
        fxprime = fxprime || [0, 0];
        var x = X[0], y = X[1];
        fxprime[0] = Math.sin(y) + Math.cos(x) * y + 2 * x;
        fxprime[1] = Math.sin(x) + Math.cos(y) * x + 2 * y;
        return fxprime;
    },

    'xDomain': [-6, 6],
    'yDomain': [6, -6]
};