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Re: g77 large array


On Tuesday, October 14, 2003, at 08:00 PM, Robert Dewar wrote:

In this case, two arrays do not need memory at the same time.
Cannot SUBROUTINE B use the same memory area as A in Fortran compiler,
even if I do not declare explicitly COMMON I?

Usually convention in Fortran is to allocate all storage statically. So indeed
one would not expect these two arrays to overlap. I am not sure about the current
Fortran standard, but earlier Fortran standards certainly *allowed* stack allocation
of such arrays, but in practice, static allocation (also certainly allowed) was
so standard, that all compilers do static allocation.

Actually, most modern Fortran compilers have a switch to control this. g77 documents
-fautomatic to do what you want. I haven't tried it; the doc also claims it is the default, so
it may not be working right in your environment, or it may have some limit on how much
stack space it will allocate.



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