On 29/07/15 15:27, ryguy7272 wrote: > On Wednesday, July 29, 2015 at 10:21:35 AM UTC-4, ryguy7272 wrote: >> On Wednesday, July 29, 2015 at 9:59:10 AM UTC-4, ryguy7272 wrote: >>> I am using Spyder Python 2.7. I'm running this sample code. >>> >>> import scipy as sp >>> cashflows=[50,40,20,10,50] >>> npv=sp.npv(0.1,cashflows) >>> round(npv,2) >>> >>> >>> Now, I'm trying to get the NPV, and I don't see any obvious way to get it. >>> The author of the book that I'm reading gets 144.56. I think that's wrong, >>> but I don't know for sure, as Python won't do any calculation at all. It's >>> easy to enter code and run it, but I can't tell how to get Python to >>> actually DO the calculation. >>> >>> Any idea what I'm doing wrong? >> >> PERFECT!! SO SIMPLE!! >> I don't know why the author didn't do that in the book. >> >> Thanks! > > One last thing, for Excel users, leave out the initial CF. Do the NPV on the > other CFs, and then add in the initial CF at the end of the NPV function. > It's almost like a PV + 1stCF. I don't know why Excel does it like that... >
I don't know what Excel does, but the first value shouldn't require any special treatment, 1.1**0 = 1. >>> sum([x/(1.1)**i for i, x in enumerate([50,40,20,10,50])]) 144.55638276074038 >>> Duncan -- https://mail.python.org/mailman/listinfo/python-list
