Fortran runtime error while reading a file: "Bad repeat count"

Question

I'm trying to read an input file with fortran but I get the following error at runtime:

At line 118 of file prog.f90 (unit = 53, file = 'data.dat')
Fortran runtime error: Bad repeat count in item 1 of list input

The data file is the following

3, 5, 3 %comment
%%%%%%%%%%%%%%
1d0, 0d0, 0d0 % comment
0d0, 0d0, 1d0 
%%%%%%%%%%%%%%
1, 1, identity, 1, 1 %comment
1, 2, sigmax, 2, 2
2, 3, sigmax, 2, 2
1, 3, sigmaz, 1, 3
3, 3, identity, 1, 1
%%%%%%%%%%%%%%
0, 0            %comment

and the interesting part of prog.f90 is

COMPLEX(KIND(1D0)), DIMENSION(:), ALLOCATABLE:: H1, H2
INTEGER :: i,A,B,C
CHARACTER(50) :: GHOST

OPEN(UNIT=53,file='data.dat',status='old')
READ(53,*) A,B,C
READ(53,*) GHOST
ALLOCATE (H1(A),H2(A))
READ(53,*) (H1(i), i=1,A)
READ(53,*) (H2(i), i=1,A)

where the 118th line is READ(53,*) (H1(i), i=1,A). I tryed also with an explicit do loop but with the same result.

Answer 1

I haven't tested this, but I'd expect

READ(53,*) (H1(i), i=1,A)

to try to read 3 complex numbers. It gets fed the line

1d0, 0d0, 0d0 % comment

from which it gets 1½ complex numbers and then barfs on the % sign, misinterpreting it as a syntactically invalid repeat count.

I'd suggest providing 3 complex numbers in the file when that read statement is executed.

Answer 2

The numbers are dimensioned complex, while in fortran complex numbers should be in the file with parenthesis as: ( realpart , imaginarypart ) ( realpart , imaginarypart )

I really don't know what the standards say regarding the input form you have presented, but after some testing gfortran throws that Bad repeat count error regardless of the % comment. It throws that error even with four or more comma separated reals on the line.

Now ifort on the other hand reads the line just the way you have it -- but watch out -- it reads each of the comma separated values as the real part of your complex variable, setting the imaginary part to zero. ( that is it only uses the first two values on each line and discards the third )

You will really need to study the code to make sure you understand what was intended to sort out how to fix this. If the later (ifort) behavior is the intention one simple fix would be to declare a couple of reals. Read into the reals, then assign those to your complex variables.