Re: how to "translate" dynamic array in FORTRAN 90 to Java code?

Shawn wrote:
Hi,

I am translating a Fortran program to Java code. Starting FORTRAN 90, an
array size can be un-specified, for example:

DIMENSION PS(*)

is an array with size unspecified. On the run-time, its size can be
increased automatically if needed.

Previously, I use Object array in Java to translate FORTRAN array. But
now, array in Java have to be fixed size.

If I use collections in Java, like Vector or ArrayList, the problem is,
as stated in my posting previously and copied to below:


Vector vec = new Vector();
vec.add(0, new Integer(4));
vec.add(1, new Double(4.4));
vec.add(2, "How are you?");
vec.add(5, "morning");

The last one is one error and the program cannot run. I purposely
skipped a couple positions.
There is a reason that I need skipping: I am "translating" Fortran code
to Java. In the original Fortran code, it takes an array several item
positions to hold a long string, like "How are you?". In Java, it only
needs one item position to hold it. I hope to keep index in Fortran and
Java correspondent, so I need skipping to let several item positions
unused. But the program will not run now.

Maybe I need:
vec.add(3, null);
vec.add(4, null);

?

Thank you again for your help.

Hi Shawn,

I think both you and some of the posters responding may have a
misunderstanding about
the meaning of the Fortran specification.

There are two kinds Fortran array specifications where the size is not
given.

The notation

real array(*)

is normally used when the array is a parameter of a subroutine, and the
real dimension will be specified in the argument...

E.g.,

program main
real myArray(100)
call sub(myArray)
end

subroutine sub(array)
real array(*)
...
end

This is exactly analagous to

void method() {
float[] myArray = new float[100];
sub(myArray);
}
void sub(float[] array) {
...
}

Fortran also has dynamically allocated arrays where the
size is determined at run time and the array
can be reallocated. I'm a bit rusty on the syntax here but it's
something like.

real, allocatable :: myArray(:)
...
allocate(myArray(2*n))
...
deallocate(myArray)
....
allocate(myArray(3*n))
...

This corresponds in Java to something like:

float[] myArray;
...
myArray = new float[2*n];
...
...
myArray = new float[3*n];
...



I'm pretty sure that anything like:

program main
real myArray(*)
myArray(3) = 3.14
end
or
real myArray(3)
myArray(5) = 25
end


are illegal in all versions of the Fortran standard. Neither Fortran
nor Java provides for automatic extensions of arrays when
a user asks for an element beyond the end of the allocated array.

So your job in translating from Fortran to Java may be a bit easier
than you have been led to believe...

Regards,
Tom McGlynn

.

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