Wed 30 Jun 2021 : in poly_gcd.h and poly_gcd.c, renamed the gcd function
  into rootsGCD to resolve a conflict with a gcd in mixed_volume1.c.
  Updated ts_gcd.c as well.  Renamed the function feedback in ts_feedback.c
  into feedback2 to avoid a naming conflict with feedback.c.
  Copied the skip function from pieri_sols into feedback.c as skip_info
  because in need for the linker of phctop in the ../Main folder.

Mon 31 Dec 2018 : took care of compiler warnings.  Fixed typo in timer.h.  
  Fixed function declarations in ts_multiply.c and ts_divide.c.
  Added #include <ctype.h> in pieri_sols.c and added "include "pieri_sols.h"
  to feedback.c, ts_feedback.c, ts_explore_poles.c, ts_explore_Cpoles.c,
  and ts_gcd.c, for the implicit declaration of the function skip().
  Added #include "poly_matrix.h" to poly_smith.c and poly_hermite.c.
  Added #include "dc_roots.h" to ts_gcd.c.
  In poly_dcmplx.c, replaced the "return;" with "return result"
  in the exceptional cases of a zero denominator.

Thu 21 Jul 2016 : formatted code in feedback.c

Sun 19 Dec 2010 : inserted "#include <stdlib.h>"
  in the file c2ada_poly_matrix.c, dc_matrix.c, pieri_sols.c, poly_hermite.c
  poly_matrix.c, poly_smith.c, and realization.c because of
  GNAT GPL 2010 warnings.

Tue 13 Jun 2006 : had to change poly_smith.c, line 285 for gcc 3.4.

Mon 6 Sep 2004 : updated feedback.c, copied files from Yusong's directory,
  changed the return type of pieri_sols from void to int.  For Mac OS X,
  changed ts_interpolation.c, ts_poly_inverse.c, and ts_timer.c.

Tue 31 Aug 2004 : created feedback.c to be called by mainfeed from phc -k

Tue 27 Jan 2004
   pieri_sols.c: semicolons are added after printing out the solution
                 array for MATLAB input.
   verify.m: prints out the solution array for each solution verification.
