Add checks on work and iwork

[jvdp1]

@wclodius2 Here are some additions for checks on work and iwork

[wclodius2]

Change "work array too small" to "work array is too small". Technically in stdlib_sorting_sort_index iwork can be present independent of work, but you assume that iwork is present only if work is present. The error stops for iwork should be "iwork array is too small" not "work array too small".

[jvdp1]

Change "work array too small" to "work array is too small". .... The error stops for iwork should be "iwork array is too small" not "work array too small".

Done.

Technically in stdlib_sorting_sort_index iwork can be present independent of work, but you assume that iwork is present only if work is present.

I am not sure that I understand your comment. Here is the structure in stdlib_sorting_sort_index:

! If necessary allocate buffers to serve as scratch memory.
        if ( present(work) ) then
            if ( size(work, kind=int_size) < array_size/2 ) then
                error stop "work array is too small."
            end if
            if ( present(iwork) ) then
                if ( size(iwork, kind=int_size) < array_size/2 ) then
                    error stop "iwork array is too small."
                endif
                call merge_sort( array, index, work, iwork )
            else
                allocate( ibuf(0:array_size/2-1), stat=stat )
                if ( stat /= 0 ) error stop "Allocation of index buffer failed."
                call merge_sort( array, index, work, ibuf )
            end if
        else
            allocate( buf(0:array_size/2-1), stat=stat )
            if ( stat /= 0 ) error stop "Allocation of array buffer failed."
            if ( present(iwork) ) then
                if ( size(iwork, kind=int_size) < array_size/2 ) then
                    error stop "iwork array is too small."
                endif
                call merge_sort( array, index, buf, iwork )
            else
                allocate( ibuf(0:array_size/2-1), stat=stat )
                if ( stat /= 0 ) error stop "Allocation of index buffer failed."
                call merge_sort( array, index, buf, ibuf )
            end if
        end if

This structure allows all possibilities:

1. (present(work),present(iwork)),
2. (present(work),.not.present(iwork)),
3. (.not.present(work), present(iwork)),
4. (.not.present(work), .not.present(iwork))

Or do I miss something?

[wclodius2]

You are right there is no assumption that iwork require work.

[wclodius2]

Looks Good!

[jvdp1]

Looks Good!

Thanks. From my side, you can merge it.

[wclodius2]

I think I have merged.