Hello,

Can anyone tell me why this Maple phaseportrait command returns the error below ? Thanks in advance !

with(DEtools);
phaseportrait(-2*x*y, [x, y], x = -1.5 .. 1.5, {[0, -2], [0, -1], [0, 0], [0, 1], [0, 2], [0, 3]}, y = -1 .. 3);
Error, (in DEtools/phaseportrait) system must have same number of dependent variables as DE's.