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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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 Posted: 18 Jan 2008 11:39:43 pm Post subject: |
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Hey, I have the Finance pkg. from TI, but there is no Net present value, or future val.
is there an add in, or app that I can use to add advanced finance functions?
Thanks. |
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simonzack
Advanced Newbie
Joined: 25 Dec 2007
Posts: 71
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| Posted: 19 Jan 2008 12:03:08 am Post subject: |
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| I'm not too familiar with that package, but if you can't really find any, you need to look for programs besides TI itself, like in the TIcalc.org archives |
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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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| Posted: 19 Jan 2008 10:20:43 am Post subject: |
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Yes, I've looked there, I have seen a few people complain about the lack of NPV, but no program to use.
I have no idea how to write one, but it may be worth learning, it is not that complicated a formula, but can be long.
What kills me is it is available on the ti83/84. I bought the 89 because I expected the most options and functions.
Right now I carry two calculators, financial, and graphing, a bit of a pain. |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 19 Jan 2008 11:12:25 am Post subject: |
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Here's a function that will calculate npv():
Define npv(i,cf0,cflist)=cf0+Σ(cflist[j](1+i)^-j,j,1,dim(cflist))
This does not have the frequency list functionality of the TI-83 Plus npv( command. If you want to use frequency lists, you could do this (which is a good bit more complicated):
npv_f(i,cf0,cflist,freq)
Func
Local cumfreq
augment({0},cumSum(freq))->cumfreq
Return cf0+Σ(cflist[j](1+i)^-cumfreq[j](1-(1+i)^-freq[j])/i,j,1,dim(cflist))
EndFunc
Last edited by Guest on 30 Aug 2010 08:21:46 pm; edited 1 time in total |
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thornahawk
μολών λαβέ
Active Member
Joined: 27 Mar 2005
Posts: 569
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| Posted: 19 Jan 2008 11:22:21 am Post subject: |
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Shouldn't that be (1+i)^-cumfreq[j], if we're going to follow the formula in the TI-83+ manual?
thornahawk |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 19 Jan 2008 11:46:47 am Post subject: |
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It should... typo!
And there was a point at which I invented a magic syntax for cumSum( that did what I wanted it to do, rather than what it's supposed to do. Also fixed.
Last edited by Guest on 19 Jan 2008 11:50:27 am; edited 1 time in total |
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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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| Posted: 19 Jan 2008 12:58:18 pm Post subject: |
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DarkerLine wrote: Here's a function that will calculate npv():
Define npv(i,cf0,cflist)=cf0+Σ(cflist[j](1+i)^-j,j,1,dim(cflist))
This does not have the frequency list functionality of the TI-83 Plus npv( command. If you want to use frequency lists, you could do this (which is a good bit more complicated):
npv_f(i,cf0,cflist,freq)
Func
Local cumfreq
augment({0},cumSum(freq))->cumfreq
Return cf0+Σ(cflist[j](1+i)^-cumfreq[j](1-(1+i)^-freq[j])/i,j,1,dim(cflist))
EndFunc
[post="119073"]<{POST_SNAPBACK}>[/post]
Hi, thanks for the reply.
Does the cumfreq go in the original function?
I have put it in both ways, with it I get data type error, without It just displays what I have typed in. i.e.
finance\npv(10,0,200) returns the same thing with Done under it. I am a total Noob in this, so please don't hesitate to talk at a 5 yr old level, and thank you for your time.
Last edited by Guest on 30 Aug 2010 08:22:06 pm; edited 1 time in total |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 19 Jan 2008 01:14:57 pm Post subject: |
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Go to the finance folder, and enter the line that starts with "Define..." on the homescreen, this will create the function npv(. It should not have a "cumfreq".
Note, however, that the third argument is a list. So you would enter finance\npv(10,0,{200}). Or, you can use a list of several values.
You can also define the function using the program editor, in which case you would enter this:
npv(i,cf0,cflist)
:cf0+Σ(cflist[j](1+i)^-j,j,1,dim(cflist))
Or, more formally:
npv(i,cf0,cflist)
:Func
:Return cf0+Σ(cflist[j](1+i)^-j,j,1,dim(cflist))
:EndFunc
The second function I gave, npv_f, should be entered through the program editor.
Last edited by Guest on 30 Aug 2010 08:21:30 pm; edited 1 time in total |
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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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| Posted: 19 Jan 2008 01:27:09 pm Post subject: |
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Sucess!!! Thank you. results match the finance calc.
No more carrying two calcs. Hmm, what else can I add to this thing?
Thanks again for the help. |
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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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| Posted: 19 Jan 2008 01:28:21 pm Post subject: |
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| of course I just killed an hour and a half of HW time... |
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sean
Newbie
Joined: 18 Jan 2008
Posts: 6
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| Posted: 19 Jan 2008 01:32:20 pm Post subject: |
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| this is sweeeet, I can see all fin. variables on the screen and do what ifs. |
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thornahawk
μολών λαβέ
Active Member
Joined: 27 Mar 2005
Posts: 569
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| Posted: 22 Jan 2008 02:08:47 am Post subject: |
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You might want to look for the book "Financial Numerical Recipes" if you're interested in extending the functionality of your TI 89 for finance-related calculations.
thornahawk |
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jack upton
Newbie
Joined: 30 Apr 2008
Posts: 1
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68k Calculator Basic => TI-BASIC
