func[] fwddiff s[] n .
for i to n
for j = 1 to len s[] - 1
s[j] = s[j + 1] - s[j]
.
len s[] -1
return s[]
s[] = [ 90 47 58 29 22 32 55 5 55 73 ]
print fwddiff s[] 1
print fwddiff s[] 2
print fwddiff s[] 9