# I need help in programing in FOTRAN 90

1. May 7, 2012

### jonephy

Hi
I have written a program in FOTRAN for solving special system called Tridiagonal system
has 5 equation
I'm in the learning stage of FOTRAN 90
and this my program::

program triiagonal
implicit none
real, dimension A(5,5),B(5,5),f(5),X(5)
integer::n,i,j,m,k,l,s1,s2
print*,"input the number of element(n)"
do i=1,n
do j=1,n+1
print*,"input the matrix a(i,j)"
end do
end do
m=n*(n-1)/2
do i=2,n
do k=1,n-1
if(A(i,j)/=0)then
do j=1,n+1
A(i,j)=A(i,j)-f(i,k)*A(j,k)
end do
else
do l=i-1,i-1
do j=1,n+1
b(i,j)=a(i,j)
a(i,j)=a(i+1,j)
a(i+1,j)=b(i,j)
end do
end do
end if
do i=n,1,-1
do j=i+1,n
s2=s2+A(i,j)*(j)
end do
s1=a(i,n+1)
x(i)=(s1-s2)/a(i.i)
end program triiagonal

this my error::
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(3): error FOR3852: syntax error detected between DIMENSION and A
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(10): error FOR3701: symbol A is not a variable
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(18): error FOR3712: symbol A is not an array
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(24): error FOR3712: symbol A is not an array
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(25): error FOR3712: symbol A is not an array
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(29): error FOR3541: duplicated DO index variable - I
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(34): error FOR3251: symbol I is not a derived type detected between % and I
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(36): error FOR3597: missing 3 END DO statements
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(36): error FOR2290: implicit type for X
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(36): error FOR2290: implicit type for F
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(36): error FOR2290: implicit type for B
C:\Documents and Settings\eXtreme\Desktop\New Folder\ffff\fff.f90(36): error FOR2290: implicit type for A

Thanks

2. May 7, 2012

### gsal

Replace this:
Code (Text):

real, dimension A(5,5),B(5,5),f(5),X(5)

with this:
Code (Text):

real, dimension(5,5) :: A,B
real, dimension(5) :: f,X

and try again.

3. May 8, 2012

### jonephy

ooooooh no ....... the same errors !!?

4. May 8, 2012

### gsal

please repost source, use code tags

5. May 8, 2012

### jonephy

Code (Text):
program  tridiagonal
implicit none
real, dimension  A(5,5),B(5,5),f(5),X(5)
integer::n,i,j,m,k,l,s1,s2
print*,"input the number of element(n)"
do i=1,n
do j=1,n+1
print*,"input the matrix a(i,j)"
end do
end do
m=n*(n-1)/2
do i=2,n
do k=1,n-1
if(A(i,j)/=0)then
do j=1,n+1
A(i,j)=A(i,j)-f(i,k)*A(j,k)
end do
else
do l=i-1,i-1
do j=1,n+1
b(i,j)=a(i,j)
a(i,j)=a(i+1,j)
a(i+1,j)=b(i,j)
end do
end do
end if
do i=n,1,-1
do j=i+1,n
s2=s2+A(i,j)*(j)
end do
s1=a(i,n+1)
x(i)=(s1-s2)/a(i.i)

end program  tridiagonal

my program in attachment ........

File size:
425 bytes
Views:
113
6. May 8, 2012

### gsal

o.k., so, you did not implement what I suggested...no wonder you are getting the same errors!

7. May 8, 2012

### jonephy

No No ...... This my .... i implemented what you suggested :)
But i am getting the same errors ,,,,,,, so i post the program before Modifying >>
^_^
Bye

8. May 8, 2012

### Staff: Mentor

Then what does your code look like now?

9. May 8, 2012

### gsal

jonephy:

please try to be more careful and let it be you who does the double checking of things...we are here to guide you, not to do the work for you.

please double check what you are doing and make sure you implemented the changes I suggested earlier.

also, you have a mess with your do-loops and the loop variables....step back and double check all that; there are also a couple of "end do" missing.

10. May 9, 2012

### jonephy

Thanks all
Ok, i will be more careful
and i will trying to fix all problems in my program
>>>>
Good Bye