Function: polcoeff
Section: polynomials
C-Name: polcoeff0
Prototype: GLDn
Help: polcoeff(x,n,{v}): coefficient of degree n of x, or the n-th component
 for vectors or matrices (for which it is simpler to use x[]). With respect
 to the main variable if v is omitted, with respect to the variable v
 otherwise.
Description:
 (pol, 0):gen:copy      constant_term($1)
 (gen, small, ?var):gen polcoeff0($1, $2, $3)
Doc: coefficient of degree $n$ of the polynomial $x$, with respect to the
 main variable if $v$ is omitted, with respect to $v$ otherwise.  If $n$
 is greater than the degree, the result is zero.

 Naturally applies to scalars (polynomial of degree $0$), as well as to
 rational functions whose denominator is a monomial.
 It also applies to power series: if $n$ is less than the valuation, the result
 is zero. If it is greater than the largest significant degree, then an error
 message is issued.

  For greater flexibility, $x$ can be a vector or matrix type and the
  function then returns \kbd{component(x,n)}.