JACOBI2

 !Program name: JACOBI2

Integer :: i, j, k, n

Real, allocatable :: A(:,:)

Real, allocatable :: X0(:), X(:), B(:)

Real :: tol, norm, sigma

Print *, "Enter the dimension of the system of non-homogeneous equations"

Read *, n

 

allocate(A(n,n))

Allocate (X0(n))

Allocate (X(n))

Allocate (B(n))

 

Do i=1,n

   Do j=1,n

     Print *, 'A(',i,',',j,')= '

     Read *, A(i,j)

   End do

end do

do i=1,n

     write (*,*) (A(i,j),j=1,n)

end do

print *,

 

do i=1,n

   Print *, 'B(',i,')='

   Read *, B(i)

end do

write (*,*) (B(j),j=1,n)

Print *,

 

do i=1,n

   Print *, 'X0(',i,')='

   Read *, X0(i)

end do

write (*,*) (X0(j),j=1,n)

Print *,

 

k=0

tol=1.0E-06

 

10 do i=1,n

    sigma=0

    do j=1,n

      If (j .ne. i) sigma=sigma+A(i,j)*X0(j)

    end do

  X(i)=(B(i)-sigma)/A(i,i)

  end do

k=k+1

print *, k, (X(i), i=1,n)

norm=abs(X(1)-X0(1))

do i=1,n

If (abs(X(i)-X0(i)) .gt. norm) then

norm=abs(X(i)-X0(i))

if (norm .lt. tol) go to 20

end if

end do

do i=1,n

X0(i)=X(i)

end do

go to 10

20 stop

end

 

!THE FINAL RESULT IS:  k=13   0.186119888    0.33123031    -0.422271289