Call the prod function: Calculate the factorial of eight. To do that, generate an array with values 1 to 8 and call the prod function on it:

b = numpy.arange(1, 9)
print "b =", b
print "Factorial", b.prod()

Check the result with your pocket calculator:

b = [1 2 3 4 5 6 7 8]
Factorial 40320

This is nice, but what if we want to know all the factorials from 1 to 8?

Call cumprod: No problem! Call the cumprod method, which computes the cumulative product of an array:

print "Factorials", b.cumprod()

It's pocket calculator time again:

Factorials [ 1 2 6 24 120 720 5040 40320]