Singular

7.5.14.0. dmodGeneralAssumptionCheck

Usage:

dmodGeneralAssumptionCheck();

Return:

nothing, but checks general assumptions on the basering

Note:

This procedure checks the following conditions on the basering R and prints an error message if any of them is violated:
- R is the n-th Weyl algebra over a field of characteristic 0,
- R is not a qring,
- for all 1<=i<=n the identity var(i+n)*var(i)=var(i)*var(i+1)+1 holds, i.e. the sequence of variables is given by
x(1),...,x(n),D(1),...,D(n), where D(i) is the differential operator belonging to x(i).

LIB "dmodloc.lib";
ring r = 0,(x,D),dp;
dmodGeneralAssumptionCheck(); // prints error message
==>    ? Basering is not a Weyl algebra
==>    ? leaving dmodloc.lib::dmodGeneralAssumptionCheck (0)
def W = Weyl();
setring W;
dmodGeneralAssumptionCheck(); // returns nothing