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5.1.70 lead

Syntax:
lead ( poly_expression )
lead ( vector_expression )
lead ( ideal_expression )
lead ( module_expression )
Type:
the same as the input type
Purpose:
returns the leading (or initial) term(s) of a polynomial, a vector, resp. of the generators of an ideal or module with respect to the monomial ordering.
Note:
IN may be used instead of lead.
Example:
 
  ring r=32003,(x,y,z),(c,ds);
  poly f=2x2+3y+4z3;
  vector v=[2x10,f];
  ideal i=f,z;
  module m=v,[0,0,2+x];
  lead(f);
==> 3y
  lead(v);
==> [2x10]
  lead(i);
==> _[1]=3y
==> _[2]=z
  lead(m);
==> _[1]=[2x10]
==> _[2]=[0,0,2]
  lead(0);
==> 0
See ideal; leadcoef; leadexp; leadmonom; module; poly; vector.