block or variable definition of integer and memory capacity

Question

hi all does anyone have idea about this problem , i have a code that runs nicely for 3000 element mesh but when i want to run it for 17000 element mesh it shows me this error: a common block or variable may not exceed 2147483647 bytes

this is some parts of code:

PARAMETER(NDIM=398316702)

integer   IA(NDF+1),LPIVTC(NDF),JA(NDIM)

DIMENSION AA(NDIM)

and it shows the error for

DIMENSION AA(NDIM)

why is it in that way?

Answer 1

This isn't a characteristic of Fortran per se, but rather your particular compiler or operating system. Note that 2147483647 = 2^31 - 1 or 2 gigabits. Probably you have a 32-bit OS and it is unable to allocate larger amounts of memory. As to why you can't get a full 2^32, perhaps something is using a signed rather than unsigned integer to store addresses and one bit is unavailable.