def train(X, Y, n_batch, eta, n_epochs, W, b, l):

    vX, vY, vy = unpackData(vFileName)

    costs = []
    vCosts = []
    i = 0
    while i < n_epochs:
        j = 0
        while j < np.shape(X)[1]/n_batch:
            j_start = j * n_batch
            j_end = (j+1) * n_batch
            Xbatch = X[:, j_start:j_end]
            Ybatch = Y[:, j_start:j_end]
            P = evaluateClassifier(Xbatch, W, b);
            grad_W, grad_b = computeGradients(Xbatch, Ybatch, P, W, l)
            W = W - eta * grad_W;
            b = b - eta * grad_b;
            j += 1
        c = computeCost(X, Y, W, b, l);
        vC = computeCost(vX, vY, W, b, l);
        print(i, ". Cost: ", c)
        costs.append(c)
        vCosts.append(vC)
        i += 1
    return costs, vCosts, W, b