The command > contourplot(-1,x=0..1,y=0..1,contours=[0],filled=true); is supposed to fill the whole space with red (color for negative values) but it does nothing this is also problem once I need to define a piecewise function which is constant according to some condition, e.g. > f:=(x,y)->piecewise(x>1/2,x*y,-1); > contourplot(f(x,y),x=0..1,y=-1..1,contours=[0],filled=true); this should fill the entire half plane x>1/2 with red, it fills only part of the first quadrant...

The simpliest version of my problem is this: > f:=(x,y)->fsolve(sin(x+y+z)=1,z) > f(5,5); still ok but now: > plot(f(x,5),x=5..10); sais: "Error, (in fsolve) x is in the equation, and is not solved for" it seems as Maple would not first evaluate x:=5 and then solve f(x) :'(