##### 7.7.4.0. checkRoot

Procedure from library `dmod.lib` (see dmod_lib).

Usage:
  checkRoot(f,alpha [,S,eng]); poly f, number alpha, string S, int eng

Return:
  int

Assume:
  Basering is a commutative ring, alpha is a positive rational number.

Purpose:
  check whether a negative rational number -alpha is a root of the global
  Bernstein-Sato polynomial of f and compute its multiplicity,
  with the algorithm given by S and with the Groebner basis engine given by eng.

Note:
  The annihilator of f^s in D[s] is needed and hence it is computed with the
  algorithm by Briancon and Maisonobe. The value of a string S can be
  'alg1' (default) - for the algorithm 1 of [LM08]
  'alg2' - for the algorithm 2 of [LM08]
  Depending on the value of S, the output of type int is:
  'alg1': 1 only if -alpha is a root of the global Bernstein-Sato polynomial
  'alg2': the multiplicity of -alpha as a root of the global Bernstein-Sato
  polynomial of f. If -alpha is not a root, the output is 0.
  If eng <>0, `std` is used for Groebner basis computations,
  otherwise (and by default) `slimgb` is used.

Display:
  If printlevel=1, progress debug messages will be printed,
  if printlevel>=2, all the debug messages will be printed.

Example:

    LIB "dmod.lib";
    printlevel=0;
    ring r = 0,(x,y),Dp;
    poly F = x^4+y^5+x*y^4;
    checkRoot(F,11/20);    // -11/20 is a root of bf
    ==> 1
    poly G = x*y;
    checkRoot(G,1,"alg2"); // -1 is a root of bg with multiplicity 2
    ==> 2

User manual for Singular version 4-0-3, 2016, generated by texi2html.