GDF_RANGE

Function gdf_range converts an input range to a valid output one given a total number of items. It is a generic function, accepting any kind of integers.

interface gdf_range
  function gdf_range(nc,nchan)
    use gbl_message
    !---------------------------------------------------------------------
    ! @ public
    ! GDF API
    !       Return a range of (pixel / channel / items)
    !       Any Kind of integers is accepted
    !---------------------------------------------------------------------
    integer(4) :: gdf_range  ! Intent(out)  0 if no error
    integer(kind=*), intent(in) :: nchan     ! The actual number of channels
    integer(kind=*), intent(inout) :: nc(2)  ! The interpreted range of selected channels
  end function gdf_range
end interface

Positive values of nc indicate an absolute channel number, while negative values are offsets from the last channel. Null values default to 1 (first channel) and nchan (last channel) respectively.