REAL :: n=10, list(n)

list = ( 90, 47, 58, 29, 22, 32, 55, 5, 55, 73 )
WRITE(Format='i1, (i6)') 0, list

DO i = 1, n-1
  ALIAS(list,1,  diff,n-i) ! rename list(1 ... n-i) with diff
  diff = list($+1) - diff  ! $ is the running left hand array index
  WRITE(Format='i1, (i6)') i, diff
ENDDO

END