/********* smvp.cc ************

smvp computes a sequence of matrix vector products and uses
them to compute the minimum polynomial of matrix A.  

Version 1.  Illustrates forming a new communicator

The name of a file containing A is given in a command line parameter.
in file (u, A, v, root, comm ) computes 

Requires 2 or more processes.
*******************************

One process stays out of the new communicator.  It's role is to use the 
matrix vector products produced by the other processors to compute a 
vector m, which stores the coefficients of the "minimum polynomial" of the
given matrix.  This process needs a sequence of vectors of the form wi = A^i v).
[ wi is the vector obtained from v by multiplying i times by A: A*A*...*A*v.]

Each time this process receives a new vector wi, it updates it's computation
of the minpoly using a function minpolystep().

********** smvp.cc ***********/

main()
{
  if ( r == 0 ) initialize_data( A, v, argv[1]);
 
  make communicator mvp-comm which excludes process p-1.

  if ( r != p-1 ) // I'm a mvp process 
  {
    process 0 send v to process p-1, who calls it w 
    distribute_data( A, v, mvp-comm );
    for (int i = 1; i < 2n; i++ )
    {  compute v <-- Av in mvp-comm
       process 0 send v to process p-1, who calls it w 
    }
    process 0 receive and print result m from process p-1.
  }
  else // I'm special process to use the vector sequence A^i v to make m.
  {
    for (int i = 0; i < 2n; i++ )
    {
      process 0 send v to process p-1, who calls it w 
      minpolystep(w, i, m);
    }
    process 0 receive and print result m from process p-1.
  }
}