construct arrays from pointer

[mariospapa]

Suppose that you have an array A(2,6,10). Is it possible to construct a second array B(2,6) from pointers p1, p2?

p1 => A(1,1:6)
p2 => A(2,1:6)

[mecej4]

There are many ways in which this can be done. Here is one that you can try to find out if it meets your needs.

I have ignored the ",10" part of your description of array A, just as your assignments to p1 and p2 did.

[fortran]program tptr

integer, dimension(2,6),target :: A, B
integer, pointer, dimension(:) :: p1,p2

data A/11,21,12,22,13,23,14,24,15,25,16,26/

p1 => A(1,:)     ! p1 and p2 are 1-D arrays
p2 => A(2,:)
B = reshape((/ p1, p2 /),(/2,6/))  !assemble the pieces into B

write(*,'(1x,6I4)')B

end program tptr

[/fortran]

[mariospapa]

Thanks mecej!

Is it possible to do the same by avoiding the decleration of array B?

[mecej4]

I don't understand what "do the same" is intended to mean, but the following modification (with references to array B removed) runs fine:

[fortran]program tptr

integer, dimension(2,6),target :: A
integer, pointer, dimension(:) :: p1,p2

data A/11,21,12,22,13,23,14,24,15,25,16,26/

p1 => A(1,:)     ! p1 and p2 are 1-D arrays
p2 => A(2,:)

write(*,'(1x,6I4)')reshape((/ p1, p2 /),(/2,6/))

end program tptr

[/fortran]

[jimdempseyatthecove]

Be mindful that p1 and p2 in the above example are stride 2 arrays that are 1D (p1 points to every other element of A and p2 points to the other every other elements of A).

Jim

[mariospapa]

The problem is very simple:
Suppose the matrix A(2,3,:) which third dimension varies... also:

[ a11 a12 a13 ]
[ a21 a22 a23 ]

How can i extract the first two dimensions of matrix A and put them like this:

[ a11 a21 ]
[ a12 a22 ]
[ a13 a23 ]

using the 1D pointers p1, p2 which:

[p1] = [ a11 a12 a13 ]
[p2] = [ a21 a22 a23 ]

[mecej4]

If that's what you want, no need to do chopping up and reassembling or using pointers.

Use TRANSPOSE !

[mariospapa]

It's not working for non-square matrices!!!!!! I can't transpose a 3 dimension matrix!