Wilkinson

subroutine wilkinson(W, n, MDIM)
    integer MDIM
    real W(MDIM,n) ,s
    do kk  = 1, 10
    s = SECNDS(0.0)
    do k = 1, 1000
        do i = 1, n
            W(i,i) = 1
            do j = i+1 , n, 2
                W(j,i) = 1
                W(i,j) = 0
            end do
            do j = i+2 , n, 2
                W(j,i) = -1
                W(i,j) = 0
            end do
            W(i,n) = -W(i+1,1)
            W(n,n-i) = W(i+1,1)
        end do
        W(n,n) = 1
    end do
    s = SECNDS(s)
    write(*,*) s
    end do
    end



    subroutine matrix_write(A,rig, col, MDIM)
    integer MDIM, rig, col
    real A(MDIM,col)
    do i = 1, rig
        write(*,*)(A(i,j), j= 1, col)
        write(*,*)
    end do
      end



    program main
    parameter(MDIM = 1000)
    real W(MDIM,MDIM)
    write(*,*)'Inserire l''ordine della matrice:'
    read(*,*) n
    call wilkinson(W, n, MDIM)
    write(*,*)'Matrice di Wilkinson:'
    write(*,*)
c   call matrix_write(W, n, n, MDIM)
    end