Can Fortran 90 Arrays Be Dynamically Allocated Based on a Variable?

In summary, array allocation in Fortran 90 allows for the dynamic allocation of memory for arrays at runtime, providing more flexibility in size and shape. This is done using the ALLOCATE statement, a significant improvement from previous versions. Arrays can also be deallocated using the DEALLOCATE statement, improving program efficiency. Fortran 90 also allows for the allocation of arrays with different data types, but there are limitations such as only being able to allocate on the heap and not being able to allocate with negative or non-integer sizes.
  • #1
truparel
1
0
Hello forum,

I was wondering if there is a way to declare/define arrays depending on some previously defined variable.

example:

if a=2, then declare/define 2 arrays
if a=3, then declare/define 3 arrays

If doable, how does one assign names to these arrays?
 
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  • #2
what you can do is declared all 3 arrays as "allocatable", then, depending on a=2 or a=3, you go ahead and allocate as necessary.

please read up on "allocatable" and take a shot at some Fortran code. Hint: it's very, very simple.
 

1. What is the purpose of array allocation in Fortran 90?

Array allocation in Fortran 90 is used to dynamically allocate memory for arrays at runtime. This allows for more flexibility in the size and shape of arrays, making it easier to work with large and complex data sets.

2. How is array allocation different in Fortran 90 compared to previous versions?

In Fortran 90, array allocation is done using the ALLOCATE statement, which allows for dynamic allocation of memory. This is a significant improvement from previous versions where arrays had to be declared with a fixed size at compile time.

3. Can arrays be deallocated in Fortran 90?

Yes, arrays can be deallocated in Fortran 90 using the DEALLOCATE statement. This allows for the release of memory when it is no longer needed, improving the efficiency of the program.

4. Is it possible to allocate arrays of different data types in Fortran 90?

Yes, Fortran 90 allows for the allocation of arrays with different data types. This is useful when working with heterogeneous data sets, where different variables may have different data types.

5. Are there any limitations to array allocation in Fortran 90?

One limitation of array allocation in Fortran 90 is that arrays can only be allocated on the heap, not on the stack. This means that arrays can only be allocated dynamically, not statically. Additionally, arrays cannot be allocated with a negative size or with non-integer sizes.

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