PRACE NPT

      Subroutine matgen ( a, x, lda, ncol )

! ---------------------------------------------------------------------

! --- Matgen generates the entries of the matrix A and the vector x.

!     These values are chosen such that y = Ax and y = A'x can be

!     checked easily.

!     The structure of A and x are as follows:

!

!              A:       ncol                    x:

!              __________/\______________

!             /                          \

!            _                      _    _   _    _   \

!          /  |  1    1    1    1   . . . |   |  1 |   |

!          |  |  1    2    3    4   . . . |   |  1 |   |

!          /  |  1    3    5    7   . . . |   |  1 |   |

! sizes(0) \  |  1    4    7   10   . . . |   |  1 |   |

!          |  |  .    .    .    .   . . . |   |  1 |   |

!          \  |  .    .    .    .   . . . |   |  1 |   |

!          ------------------------------------------- |

!          /  |  1  m+1  2m-1 3m-2  . . . |   |  2 |    \ Each of the

!          |  |  1  m+2  2m+1 3m+1  . . . |   |  2 |    / processors

!          /  |  1  m+3  2m+3 3m+4  . . . |   |  2 |   |  contains a

! sizes(1) \  |  1  m+4  2m+5 3m+7  . . . |   |  2 |   |  strip of A

!          |  |  .   .     .   .    . . . |   |  2 |   |  sizes(i)*ncol

!          \  |  .   .     .   .    . . . |   |  2 |   |  and the full

!          ------------------------------------------- |  vector x.

!                           .                    .     |  

!                           .                    .     |

!                           .                    .     / 

! ---------------------------------------------------------------------

      Use                   dist_module

      Use                   numerics

      Integer            :: ncol

      Real(l_)           :: a(lda,ncol), x(ncol)

      Integer            :: i, im1, j, k, kbase

! ---------------------------------------------------------------------

!                                                     ** Make vector x.

      Do k = 1, nodes

         kbase = offset(k-1)

         Do i = 1, sizes(k-1)

            x(kbase+i) =  Dble( k )

         End Do

      End Do

! ---------------------------------------------------------------------

!                                                     ** Make matrix A.

      kbase = offset(me) - 1

      Do j = 1, ncol         

         Do i = 1, sizes(me)

            a(i,j) = (kbase + i)*(j - 1) + 1

         End Do

      End Do

! ---------------------------------------------------------------------

      End Subroutine matgen