Error Unclassifiable Statement at (1) in a fortran code for the Archimedes pi problem

Question

i'm doing a code in Fortran for the Archimedes aproximation of Pi. When I compile the code in the Terminal send the Unclassifiable statement error.

This is the code.

implicit none

real*8 n,P0,P,F,G,H,I,J,pi,L,x

open(10,file='valordepi.out',status='unknown')

P0=2.d0*(2.d0**(0.5d0))
P=P0

do



n=1,100

pi=acos(x)

x=-1



P(n)=P/2.d0**n

F=-P(n)**2.d0
G=(1.d0-F)**0.5d0
H=1.d0-G
I=(2.d0*H)**0.5d0
J=I*2.d0**n

P=J

L=(J-pi)/pi

write(10,*) n,J,L
end do

close(10)

The idea is check the approximation of the Archimedes solution and get the data to do the graphic. The error is in the line when i wrote n=1,100

Greetings and thanks for the help.

Answer 1

I check the code several times, and now i got it like this.

implicit none
integer n
real*8 P0,P,F,G,H,I,J,pi,L,x

open(10,file='valordepi.out',status='unknown')

P0=2.d0*(2.d0**(0.5d0))
P=P0
x=-1.d0
pi=acos(x)

do n=2,50

P=P/2.d0**n
F=P**2.d0
G=(1.d0-F)**0.5d0
H=1.d0-G
I=(2.d0*H)**0.5d0
J=I*2.d0**n
P=J
L=abs(J-pi)

write(10,*) n,J,L 
write(*,*) n,J,L
end do

close(10)

This code don't have errors, and do just what i asked. Thanks to everyone for the reply. The error I did was that the n=2,50 wasn't in the do line.