use 'math' local function rosenbrock() -- rosenbrock function local f = function(x, y) return 100*(y-x^2)^2 + (1-x)^2 end local N = 9 local function frbeval(k) return f(1, 1 - 2 * (k/N)^2) end local ls = iter.ilist(frbeval, N) local p = contour.plot(f, -1.5, -0.5, 1.5, 2, {gridx= 80, gridy= 80, levels= ls}) p.title = 'Contour plot of Rosenbrock function' return p end local function sincos() local fsincos = function(sx,sy) return function(x,y) return cos(x)+cos(y) + sx*x + sy*y end end local f = fsincos(0.1, 0.3) local p1 = contour.plot(f, -2*pi, -2*pi, 6*pi, 6*pi, {gridx=120, gridy=120, levels= 12, show= false}) p1.title = 'f(x,y) = cos(x) + cos(y) + 0.1x + 0.3y' p1:show() return p1 end local function xypolar() local N, R, zmax = 5, 1.2, 1.2 local ls = iter.ilist(|k| zmax * (k-N-1)/N, 2*N+1) local p = contour.polar_plot(|x,y| y^2 - x^2*(x+1), R, {levels= ls}) p.title = 'f(x,y) = y^2 - x^2*(x+1)' return p end return {'Contour Plots', { { name = 'contour1', f = rosenbrock, description = 'Contour plot of Rosenbrock function', }, { name = 'contour2', f = sincos, description = 'Another contour plot example', }, { name = 'contour3', f = xypolar, description = 'Polar plot example', }, }}