topic Re: Memory usage with allocate and derived type in Intel® Fortran Compiler

Memory usage with allocate and derived type

alexismor — Thu, 25 Aug 2005 01:28:03 GMT

Hello,

I have a derived type called particle that holds the quantum numbers of a partice like so:

type(particle)
integer :: m,n,s
end type particle

I then made another type to hold an array of these particles, along with another parameter called norm:

type(basis)
type(particle), allocatable :: p(:)
real*8 :: norm
end type basis

Finally, there are different ways of grouping the parameters together (there are multiple basis states) and I need to enumerate them all and remember the results. So in my main code I have something like this:

type(basis), allocatable :: b(:)

Now suppose that I have 10 basis states, and only 3 particles. The way I was initializing my b array is like:

allocate(b(10))
do i=1,3
allocate(b(i)%p(3))
enddo

However, I just noticed when using the debugger in Visual Studio that as soon as I allocate the b array, all the sub-arrays of particles are also allocated to the same size. So instead of ending up with

b(1)%p(1)
b(1)%p(2)
b(1)%p(3)
b(2)%p(1)
b(2)%p(2)
b(2)%p(3)
...
b(10)%p(1)

I get

b(1)%p(1)
...
b(1)%p(10)
b(2)%p(1)
...
b(10)%p(10)

am I doing anything wrong?

Thanks,

Alexis

Re: Memory usage with allocate and derived type

alexismor — Thu, 25 Aug 2005 01:37:16 GMT

It looks like this might just be an artifact created by MS Visual Studio. When I test a little program like:

program test
use basis_module
type(basis), allocatable :: b(:)

allocate(b(10))
allocate(b(1)%p(3))
print*,'size(b)=',size(b)
print*,'size(b(1)%p=',size(b(1)%p)
stop
end

I get the expected results.

Re: Memory usage with allocate and derived type

Zhanghong_T_ — Fri, 26 Aug 2005 02:33:54 GMT

I have the similar experience. It seems that in watch window the results displayed are wrong, but the final results of the program are correct.

Re: Memory usage with allocate and derived type

Steven_L_Intel1 — Fri, 26 Aug 2005 02:47:50 GMT

I can reproduce Alexis' problem and will let the developers know about it. It seems that the debugger is misinterpreting the information the compiler supplies.