I've got a bit of a headache with regard to passing arrays to functions and/or subroutines. My code looks more or less as follows.
program test
implicit none
integer arraySize
parameter (arraySize = 10)
integer myFunction
integer someValue
integer array1(arraySize,arraySize)
...
...
someValue = myFunction(arraySize,array1)
...
end
integer function myFunction(arraySize,array1)
implicit none
integer arraySize
integer array1(arraySize,arraySize)
...
end
I can get sub-programs of this type to compile, and do my relevant maths on values in the array. This is done with several 4 dimensional arrays, all defined in the same type of way described above.
However, I've got a subroutine where I want to pass 5 of these arrays, and do some maths on the values . I figured I'd try using a common statement to simplify the subroutine statement, instead of having each array as an argument. So I have something like the following:
program test2
implicit none
integer arraySize
parameter (arraySize = 10)
integer array1(arraySize,arraySize)
integer array2(arraySize,arraySize)
integer array3(arraySize,arraySize)
common /myArrays/ array1, array2, array3
...
call arraySum(arraySize)
...
end
subroutine arraySum(arraySize)
implicit none
integer arraySize
integer array1(arraySize,arraySize)
integer array2(arraySize,arraySize)
integer array3(arraySize,arraySize)
common /myArrays/ array1,array2,array3
...
end
I tried compiling, and I get this error
integer array1(arraySize,arraySize)
1
Error: Variable 'arraysize' at (1) in this context must be constant
I am confused for a number of reasons. Have I misunderstood how to use common statements? Surely if I can pass the size of an array to a sub-program as in my first example, then why would this method make any sort of difference; or do I need to redefine another integer in the subroutine and make this a constant equal to the value of arraySize? Or is it just a quirk of F77, and I should just grit my teeth and pass all 3 arrays over in the subroutine argument?
I apologise for the archaic style of the code, and if I've had any misunderstanding of the principles of Fortran programming (my only prior experience is with C & C++). I'd like to use something newer than F77, but it's not an option currently (student).
