Nonsense error in FORTRAN

UNIX for Beginners Q & A
1

Hello, I've been trying to set up a code for fortran, it's about integration, the problem comes when I try to compile the program, the log shows 2 errors: "Error: Expected a right parenthesis in expression " 2 times, and only in 1 shows the line in which it's apparently located (32), I'm going crazy cause i can't find the problem, does anyone know what's wrong?, the code is:

program main
  implicit none
  integer :: n,i,k
  real*8 :: a,b,x,trapecio,s,suma1,suma2,x2,formula1,formula2,eps,div,h

  !variables
  n=3
  a=0d8
  b=4d8


  !calculate the additions 1 a n-1 y 2 a n-2

  suma1=0d0
  suma2=0d0
  do n=3,300,2*n
   h=(b-a)/dble(n)

        do i=1,n-1,2
            x=a+dble(i)*h
            formula1= 1/(1+(x^2))
            suma1=  suma1 + formula1
        end do

        do k= 2,n-2,2
            x2=a+dble(k)*h
            formula2 =1/(1 + (x2^2)
            suma2= suma2+ formula2
        end do

     trapecio= h/3* &
     (1+ 4*suma1 + 2*suma2 + 1(1/n^2))
     div= trapecio/(trapecio/2)
            if (div < 1d-6) then
                exit
            end if

    write(*,*), trapecio
   end do
  end
2

Show the compilation command including all error messages. One error is here:

            formula2 =1/(1 + (x2^2)

For the rest the messages might help.

2 Likes
3

I've corrected the error you indicated before and now still appearing the same errors but doesn't show the line, the build log is:

-------------- Build: Debug in examen ejercicio2 (compiler: GNU Fortran Compiler)---------------

mingw32-gfortran.exe -Jobj\Debug\ -Wall  -g     -c "D:\Users\Luis Carlos Dorado\Desktop\examen ejercicio2\main.f95" -o obj\Debug\main.o
mingw32-gfortran.exe  -o "bin\Debug\examen ejercicio2.exe" obj\Debug\main.o   
D:\Users\Luis Carlos Dorado\Desktop\examen ejercicio2\main.f95:21:29: Error: Expected a right parenthesis in expression at (1)
D:\Users\Luis Carlos Dorado\Desktop\examen ejercicio2\main.f95:27:32: Error: Expected a right parenthesis in expression at (1)
  D:\Users\Luis Carlos Dorado\Desktop\examen ejercicio2\main.f95:32:31: Error: Expected a right parenthesis in expression at (1)

EDIT: I messed up with the exponentials so hard, thank you so much for your help sir!

4

My FORTRAN days are looooooong gone, but two of the three "error coordinates" indicate the complier might not be happy with the ^ for exponentiation. I faintly remember it being ** in those old days. Sure you got no syntax gobbledigook?

2 Likes
5 
(1+ 4*suma1 + 2*suma2 + 1(1/n^2))

Should there be an operator between 1 and (1/n^2)

2 Likes
6

You remember it well hahaha I messed up with the exponentials. I know it's an old language that's barely used but in my University they make me use it in first grade.

And yes, I corrected that too

Thank you so much for your help, finally it compiled :b: