On Fri, Apr 3, 2009 at 7:45 PM, Brian <medo...@gmail.com> wrote: > > Thank you Timothy. Here is the correct (I believe) code for that > equation. > > def units(C, n, F, r): > return sum([C / (1 + r) ^ t for t in range(1, n+1)]) + F / (1 + r) > ^ n > > def price(C, n, F, r): > return 100 * (units(C, n, F, r) / F) > > Here, units expresses the equation I linked to, and price gives the > scaled price, 100 being par. > > For example, evaluating the expression below demonstrates the example > calculation from this site: > http://www.moneychimp.com/articles/finworks/fmbondytm.htm > > units(70,4,1000,.0853) > > That evaluates to ~950 as in the example, therefore giving a price of > ~95: > > price(70,4,1000,.0853) > > And sure enough, plotting the price yield curve gives sensible > results: > plot(price(70,4,1000,var('y')),0,.2) > > Now I would like to make a 3d plot where n and r are free. The > trouble is, when I try it, I get the following error. Would someone > point out my error? > > plot(price(70,var('n'),1000,var('y'))) > > TypeError: range() integer start argument expected, got > sage.rings.integer.Integer. >
The problem is that you're giving the symbolic variable "n" as input to the range command (in your units function), but the range command takes a pair of integers as input. William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
