FUNCTION cumsum,v
;+
; s=CUMSUM(v) is a vector such that s[0]=v[0], s[1]=v[0]+v[1],..
; so that s is the cumulative sum over v. If v is an array
; with multiple dimensions, then s has the same shape as v.
;
; H. Rhody
; February 1999
;-

n=N_ELEMENTS(v)
s=v
FOR k=1,n-1 DO s[k]=s[k-1]+v[k]
RETURN,s
END