ponto = [0 0]; n = 10; amplitude = 1;
variaX = ponto(1) - amplitude: 1/n: ponto(1) + amplitude;
variaY = ponto(2) - amplitude: 1/n: ponto(2) + amplitude;
[x, y] = meshgrid(variaX, variaY);
f = (x - y.^2)*(x - 0.5*y.^2);
surf(x, y, f)
contour(x, y, f, 50)