Singular

LIB "difform.lib";
ring R = 0,(x,y,z),ds;
diffAlgebra();
==> // The differential algebra Omega_R was constructed and the differential \
   forms dx, dy, dz are available.
////////////////////////////////////
// Addition of differential forms //
////////////////////////////////////
difform df = dx + 4*dy - dz*dx + 4 + 3*dx*dy + 4*dz;
difform dg = dx + dy + 27*dz*dy;
df+dg;
==> 4+2*dx+5*dy+4*dz+3*dx*dy+dx*dz+(-27)*dy*dz
==> 
////////////////////////////////////////////////////
// Addition of polynomials and differential forms //
////////////////////////////////////////////////////
df + x2y2z2;
==> 4+x2y2z2+dx+4*dy+4*dz+3*dx*dy+dx*dz
==> 
12 + dg;
==> 12+dx+dy+(-27)*dy*dz
==> 
kill Omega_R,df,dg,dx,dy,dz;