%\starttext
\startMPcode{doublefun}
draw lmt_contour [
xmin = 0, xmax = 4*pi, xstep = .05,
ymin = -6, ymax = 6, ystep = .05,
levels = 7,
height = 5cm,
preamble = "local sin, cos = math.sin, math.cos",
function = "cos(x)+sin(y)",
%functionstyle = "math",
background = "bitmap",
foreground = "edge",
linewidth = 1/2,
cache = true,
];
\stopMPcode
%\stoptext
Thank you so much.