program test_eigenvectors
!! Program to show the usage of the the *eigenvectors* module.
use eigenvectors
implicit none
integer, parameter :: N = 3
integer :: i
real :: A(N,N), v(N), lambda1, lambda2, lambda3
character(:), allocatable :: fmt
fmt = '(F7.2)'
A(1,:) = [ 1., 0., 0. ]
A(2,:) = [ 0., -0.5, 0. ]
A(3,:) = [ 0., 0., -4.]
call eigen_max(A, v, lambda1, maxIter= 1000, err_v=1.E-6, v_0=[1.,1.,1.])
print*, "biggest eigenvalue: "
write(*,fmt=fmt) lambda1
print*, "associated eigenvector: "
do i = 1,N
write(*,fmt=fmt) v(i)
end do
call eigen_inv(A, v, lambda1, maxIter= 1000, p=0., err_v=1.E-6, v_0=[1.,1.,1.])
print*, "smallest eigenvalue: "
write(*,fmt=fmt) lambda1
print*, "associated eigenvector: "
do i = 1,N
write(*,fmt=fmt) v(i)
end do
end program
