program laplace

real, dimension(15,15) :: V1
real, dimension(15,15) :: V2

do I=1,15
        do J=1,15
                V1(I,J) = 1000*random(L)
        end do
end do

do I=1,15
V1(1,I)=0.0
end do

do I=1,15
V1(I,1) = 0.0
end do

do I=1,15
V1(15,I)=0.0
end do

do I=1,15
V1(I,15)=100.0
end do




10  do I=2,14
 
 		do J=2,14
                V1(I,J) = (V1(I-1,J)+V1(I+1,J)+V1(I,J-1)+V1(I,J+1))/4
        
        Vold(I,J)=V1(I,J)
        
        
        end do
 
 end do

  do i=2,14
  
  		do J=2,14
  		
  			if(V1(I,J)-Vold(I,J)/Vold(i,J) .GT. 0.01) THEN
  		
  			GO TO 10
  		
  			ELSE IF (i==14 .AND. j==14)
  		
  			go to 50
  		
  			end if
  		end do
  		
  end  do
  
  	50	do i=1,15
          write(*,'(1X,100G14.5)') (V1(i,j),j=1,15)
       end do

end program laplace

function random(L)
integer :: L
L = mod(1366*L+150889,714025)
Random=Real(L)/Real(7142024)
return 
end