Mercurial > octave-nkf
view scripts/finance/pv.m @ 3439:3234a698073a
[project @ 2000-01-14 09:51:14 by jwe]
author | jwe |
---|---|
date | Fri, 14 Jan 2000 09:52:35 +0000 |
parents | f8dde1807dee |
children | 434790acb067 |
line wrap: on
line source
## Copyright (C) 1995, 1996 Kurt Hornik ## ## This program is free software; you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 2, or (at your option) ## any later version. ## ## This program is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ## General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this file. If not, write to the Free Software Foundation, ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. ## -*- texinfo -*- ## @deftypefn {Function File} {} pv (@var{r}, @var{n}, @var{p}, @var{l}, @var{method}) ## Returns the present value of an investment that will pay off @var{p} for @var{n} ## consecutive periods, assuming an interest @var{r}. ## ## The optional argument @var{l} may be used to specify an additional ## lump-sum payment made at the end of @var{n} periods. ## ## The optional argument @var{method} may be used to specify whether ## payments are made at the end (@code{"e"}, default) or at the ## beginning (@code{"b"}) of each period. ## ## Note that the rate @var{r} is specified as a fraction (i.e., 0.05, ## not 5 percent). ## @end deftypefn ## @seealso{pmt, nper, rate, and npv} ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> ## Description: Present value of an investment function v = pv (r, n, p, l, m) if ((nargin < 3) || (nargin > 5)) usage ("pv (r, n, p [, l] [, method])"); endif if !(is_scalar (r) && (r > -1)) error ("pv: r must be a scalar > -1"); elseif !(is_scalar (n) && (n > 0)) error ("pv: n must be a positive scalar"); elseif !is_scalar (p) error ("pv: p must be a scalar."); endif if (r != 0) v = p * (1 - (1 + r)^(-n)) / r; else v = p * n; endif if (nargin > 3) if (nargin == 5) if !isstr (m) error ("pv: `method' must be a string"); endif elseif isstr (l) m = l; l = 0; else m = "e"; endif if strcmp (m, "b") v = v * (1 + r); endif if is_scalar (l) v = v + pvl (r, n, l); else error ("pv: l must be a scalar"); endif endif endfunction