FORTRAN 90 Unexpected Statement Function Statement in Nested Do Loop

In the following code, highlighted in bold, I am using a nested DO loop to create a running sum of the yearly emissions ("emissions") read out of histem.txt, to create a cumulative emissions curve.

The code generates an "Unexpected STATEMENT FUNCTION statement for sum in cem(i) = sum, however?

Code:
program sat_profile

! This program can be used to create a smooth temperature profile starting from
! a specified slope at the year 2005 and stabilizing (with zero slope) at 2300.
! The starting slope can be calculated from the last 10 years of the simulation
! providing the initial condition at 2005. A starting temperature and final
! temperature also need to be specified. The final target temperature should be
! the modelled preindustrial temperature plus the temperature target (1.5, 2, 3,
! and 4 degrees C). An arbitrary mid point year and temperature (between 2005
! and 2300) is also specified. This may need some adjustment in order to
! generate a smoothly changing profile without overshoot. The output is a text
! file with annual values from 2005 to 2500. This can be adjusted to provide
! interpolated values at other time intervals by changing the loop that
! generates tval and calculates yval.

implicit none

integer, parameter :: nd=3, iyr=2008, fyr = 2500
integer i, j
real t(nd), y(nd), ypp(nd), tval, yval, ypval, yppval, ybcbeg, ybcend, offset, initg

real year(257), emissions(257), HIST, TIM, sum, cem

real AEMIT(iyr:fyr), EMIT(iyr:fyr), TIME(iyr:fyr)

! input parameters: NOTE --> t(1) and t(3) MUST match iyr and fyr respectively
t(1) = 2008.               ! starting year of synthetic profile
t(3) = 2500.               ! year of zero emissions
t(2) = 2400.               ! year of peak emissions (may be adjusted)
y(1) = 346.758            ! emissions at starting year (set to year 2008)
y(3) = 2000          ! emissions at end (set to PI + target)
y(2) = 1900      ! emissions at peak (may be adjusted)
! starting slope can be derived from the last 10 years of a simulation to 2008
initg =  8.749	     ! value of EMIT(t=1) (should be the same as 2008 annual emissions in historical curve)
ybcbeg = 8.749           ! slope at t(1) (Gt year-1)
ybcend = 0.                ! slope at t(3) (zero)
offset = 0               ! time offset (half of the averaging period)
! calculate the spline derivatives
call spline_cubic_set ( nd, t, y, 1, ybcbeg, 1, ybcend, ypp )

if (t(3).lt.t(2)) then
print *, 'error, t(2) must be smaller than t(3)'
call exit(1)
endif

if (t(3).eq.t(2)) then
print *, 'error, t(2) must be smaller than t(3)'
call exit(1)
endif

if (iyr.ne.t(1)) then
print *, 'error, iyr and t(1) do not match'
call exit(1)
endif

if (fyr.ne.t(3)) then
print *, 'error, fyr and t(3) do not match'
call exit(1)
endif

open(unit=15, file='histem.txt')

258 open (10, file='cumemC.txt')
! evaluate the spline at points tval

!change 2005, 2500 to values of t(1) and t(3)

do i=1,257
sum=0
do j=1,i
sum = sum + emissions(j)
write (*, '(2f12.4)')
enddo
cem(i) = sum
write (10, '(2f12.4)') year(i), cem(i)
enddo

do i=iyr,fyr
tval = float(i)
call spline_cubic_val ( nd, t, y, ypp, tval, yval, ypval, yppval )

! if not doing stabilization, get rid of this line:
!if (tval > t(3)) yval = y(3)

if (tval.eq.t(1)) yval = y(1)

write (*, '(2f12.4)' ) tval+offset, yval
write (10, '(2f12.4)' ) tval+offset, yval
AEMIT(i) = yval
TIME(i) = tval
end do
close (10)

open(10, file='anemC.txt')
write (10, '(2f12.4)') year, emissions
EMIT(iyr) = initg

write (*, '(2f12.4)' ) TIME(iyr), EMIT(iyr)
write (10, '(2f12.4)' ) TIME(iyr), EMIT(iyr)
do i=iyr+1,fyr
EMIT(i) = AEMIT(i) - AEMIT(i-1)

write (*, '(2f12.4)' ) TIME(i), EMIT(i)
write (10, '(2f12.4)' ) TIME(i), EMIT(i)
end do

close (10)

end
Attached Files
 histem.txt (2.7 KB, 2 views)
 Mentor Change the name of your 'sum' variable. It's colliding with an intrinsic function - see http://gcc.gnu.org/onlinedocs/gfortran/SUM.html.
 Recognitions: Science Advisor The immediate issue is that "cem()" is being used as an array but is not declared as such.

FORTRAN 90 Unexpected Statement Function Statement in Nested Do Loop

Thanks!

I have now found that my read statement is going to cause some trouble too!

Looks like I am reading in year and emissions each as a one dimensional array, and then trying to re-write them as a scalar entity.

 Quote by uart The immediate issue is that "cem()" is being used as an array but is not declared as such.
Thanks!

I have now found that my read statement is going to cause some trouble too!

Looks like I am reading in year and emissions each as a one dimensional array, and then trying to re-write them as a scalar entity?

 Tags fortran, fortran 90, nested do loop