from darray import * d = DoubleArray(1000) print len(d) for i in range(0,len(d)): d[i] = 0.25*i sum = 0.0 for n in d: sum = sum + n print "sum[0:1000] = ",sum # Make a slice sum = 0.0 for n in d[500:1000]: sum = sum + n print "sum[500:1000] = ",sum del d