Hi everyone, I have difficulties doing something that should be simple. I want to define in a main program a parameter, then pass it to a subroutine where an array is created using this parameter , example below :slight_smile: program A x=5 call B(x) "and inside B" real*8 Y(X) It is not …

You do not say what is not working and your excerpt is rather terse. I include a working example below: ! autoarray.f90 -- ! Illustrate how to create automatic arrays ! program autoarray implicit none integer :: x x = 5 call print_size( x ) contains subroutine print_size( y …

If your compiler is Fortran 90 or better, have a look at https://web.stanford.edu/class/me200c/tutorial_90/07_arrays.html to learn about allocatable arrays. If you only have Fortran 77, then know that there are no dynamic arrays. You would have to declare an array at least as big as 5 elements and p…

[image] grotero1992: pass it to a subroutine where an array is created using this parameter you can see some examples in Page Redirection

Thanks enveryone, i managed to find the way to do it, in fact the size of the array was computed in the subroutine where i needed it, i just had to compute it in my main program and then pass the integer to the subroutine

Just to expand on Arjen’s notes: There are 3 main types of locally defined arrays in Fortran that allocate memory usage. Local arrays : real :: array(parameter_size) ! where parameter_size is constant or integer parameter Automatic arrays : real :: array(arg_size) ! where arg_size is an integer…

Also note the administrator can increase the allowed stack size, which on 64-bit systems has little or no significant cost. HPC Administrators almost always greatly increase the limits from the defaults if the vendors have not already done so.

The x in Romain’s program is not a parameter though Romain thought it was. In Fortran that word is used when defining a constant that cannot be altered subsequently in the program, e.g. integer,parameter:: x=5

Parameter in call for array size

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JohnCampbell December 7, 2021, 6:13am 8

This increase is severely limited on 64-bit OS, typically to 2 or 4GBytes.
We will have to wait and see if a full 64-bit OS will eventuate.

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Parameter in call for array size

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