The function call Initial(p,R) returns the initial of p with respect to the ranking of R, or of its embedding polynomial ring, if R is an ideal. It is assumed that p is non-numeric.

The function call Initial(L,R) returns the list or the set of the initials of the elements of L with respect to the ranking of R.

If ideal is a regular differential chain, the function call Initial(ideal) returns the list of the initials of the chain elements. If ideal is a list of regular differential chains, the function call Initial(ideal) returns a list of lists of initials.

This command is part of the DifferentialAlgebra:-Tools package. It can be called using the form Initial(...) after executing the command with(DifferentialAlgebra:-Tools). It can also be directly called using the form DifferentialAlgebra[Tools][Initial](...).

The opts arguments may contain one or more of the options below.

fullset = boolean. In the case of the function call Initial(ideal), applies the function also over the differential polynomials which state that the derivatives of the parameters are zero. Default value is false.

notation = jet, tjet, diff or Diff. Specifies the notation used for the result of the function call. If not specified, the notation of the first argument is used.

memout = nonnegative. Specifies a memory limit, in MB, for the computation. Default is zero (no memory out).