Singular Manual: difformIsGen

D.15.2.13 difformIsGen

Procedure from library difform.lib (see difform_lib).

Usage:: difformIsGen(df); df difform
Return:: 1, if df is a generator of the differential algebra - 0, otherwise
Remarks:: Uses the procedure difformCoef and tests for a single coefficient which is one

Example:

LIB "difform.lib";
ring R = 0,(x,y,z,a,b,c),lp;
diffAlgebra();
==> // The differential algebra Omega_R was constructed and the differential \
   forms dDx, dDy, dDz, dDa, dDb, dDc, dx, dy, dz, da, db, dc are available.
////////////////
// Generators //
////////////////
difformIsGen(1);
==> 1
difformIsGen(dx);
==> 1
difformIsGen(da*dc);
==> 1
difformIsGen(dy*da*db);
==> 1
difformIsGen(-da*dz);
==> 1
///////////////////
// No generators //
///////////////////
difformIsGen(-1);
==> 0
difformIsGen(-dx);
==> 0
difformIsGen(dc*da);
==> 0
difformIsGen(dy*db*da);
==> 0
difformIsGen(dx*dz*dy);
==> 0
kill Omega_R,dx,dy,dz,da,db,dc;