t=%pi*(-10:10)/10; deff('[z]=surf(x,y)','z=sin(x)*cos(y)'); rect=[-%pi,%pi,-%pi,%pi,-1,1]; z=feval(t,t,surf); plot3d(t,t,z,35,45,'X@Y@Z',[-20,1,3],rect); xset('alufunction',0); contour(t,t,z,10,35,45,'X@Y@Z',[0,1,0],rect); xtitle('plot3d and contour',' ',' ');