write_hdr Subroutine

        subroutine write_hdr(u, sizes, type)
            !! write out header information for .nrrd file format
            use utils, only : str

            !> data dtype
            character(*), intent(IN) :: type
            !> file handle
            integer,      intent(IN) :: u
            !> dimensions of data
            integer,      intent(IN) :: sizes(:)
            
            character(len=100) :: string
            integer :: i

            string = ""
            do i = 1, size(sizes)
                if(i == 1)then
                    string = str(sizes(i))            
                else
                    string = trim(string) // " " // str(sizes(i))
                end if
            end do

            write(u,"(A)")"NRRD0004"
            write(u,"(A)")"type: "//type
            write(u,"(A)")"dimension: "//str(size(sizes))
            write(u,"(A)")"sizes: "//trim(string)
            write(u,"(A)")"space dimension: "//str(size(sizes))
            write(u,"(A)")"encoding: raw"
            write(u,"(A)")"endian: little"

        end subroutine write_hdr