How to Calculate NPV?

Terry Reedy tjreedy at
Wed Jul 29 21:08:25 CEST 2015

On 7/29/2015 10:21 AM, 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?
> I don't know why the author didn't do that in the book.

The book show you how to calculate things.  It is up to you to display, 
output to a file, or use in further calculation.  I do admit, though, 
that snippets that show how to use an existing function, rather than 
define a new function, might benefit from adding print(xxxx).

Terry Jan Reedy

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