program CoopJ

	implicit none
	
	! Cooper-Jacob approximatation for transient head during pumping in ideal aquifer
	! ho-h(r)=(2.303Q/4piT)*log(2.25Tt/r^2S)
	! h(r)=-(2.303Q/4piT)*log(2.25Tt/r^2S)+ho
	! u=r^2S/4Tt<0.05...ish
	
	! Delcare
	
	integer :: i, j
	integer,parameter :: row=100,col=1+6+6 ! First column time, next five head, next five u
	real,parameter :: pi=3.14159
	real,dimension(row,col) :: A
	real,dimension(6) :: r
	real :: K, b, T, S, Q, ti, ho

	! Define
	
	K=28.3/3.5
	b=5.
	T=K*b
	S=0.25
	Q=-42.8
	ti=0.3125
	ho=100.+0.75
	
	r(1)=1.
	
	do j=2,6
		r(j)=(j-1.)*5.
	end do
	
	! Compute

	do i=1,row
		do j=1,col
			A(i,j)=0.
		end do
	end do	
	
	do i=1,row
		A(i,1)=i*(ti/row)
	end do

	do j=2,col-6
		do i=1,row
			A(i,j)=-(2.303*Q)/(4.*pi*T)*log10((2.25*T*A(i,1))/((r(j-1)**2.)*S))+ho
		end do
	end do
	
	do i=1,row
		do j=8,col
			A(i,j)=((r(j-7)**2.)*S)/(4.*T*A(i,1))
		end do
	end do	

	write(*,10) ((A(i,j),j=1,col),i=1,row)
	10 format(1x,13f10.4)
	
	open(unit=1000, file='CoopJ_out.txt') ! Open new or overwrite old output file
	
	write(1000,100) ((A(i,j),j=1,col),i=1,row)
	100 format(1x,13f10.4)
	
	close(1000)
	
	! Output

end program CoopJ