Mercurial > octave-nkf
view scripts/finance/npv.m @ 5249:5c2f58301790 ss-2-9-1
[project @ 2005-03-27 12:06:59 by jwe]
author | jwe |
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date | Sun, 27 Mar 2005 12:06:59 +0000 |
parents | c08cb1098afc |
children | 4c8a2e4e0717 |
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## Copyright (C) 1995, 1996, 1997 Kurt Hornik ## ## This file is part of Octave. ## ## Octave 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. ## ## Octave 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 Octave; see the file COPYING. If not, write to the Free ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA ## 02111-1307, USA. ## -*- texinfo -*- ## @deftypefn {Function File} {} npv (@var{r}, @var{p}, @var{i}) ## Returns the net present value of a series of irregular (i.e., not ## necessarily identical) payments @var{p} which occur at the ends of @var{n} ## consecutive periods. @var{r} specifies the one-period interest rates and ## can either be a scalar (constant rates) or a vector of the same ## length as @var{p}. ## ## The optional argument @var{i} may be used to specify an initial ## investment. ## ## Note that the rate @var{r} is specified as a fraction (i.e., 0.05, ## not 5 percent). ## @end deftypefn ## ## @seealso{irr and pv} ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> ## Description: Net present value of a series of payments function v = npv (r, p, i) if ((nargin < 2) || (nargin > 3)) usage ("npv (r, p, i"); endif if (! (isvector (p))) error ("npv: p has to be a vector"); else n = length (p); p = reshape (p, 1, n); endif if (any (any (r <= -1))) error ("npv: all interest rates must be > -1"); endif if (isscalar (r)) d = 1 ./ (1 + r) .^ (0 : n); elseif (isvector (r) && (length (r) == n)) d = [1, (1 ./ cumprod (reshape (1 + r, 1, n)))]; else error ("npv: r must be a scalar or a vector of the same length as p"); endif if (nargin == 3) if (! isscalar (i)) error ("npv: I_0 must be a scalar"); endif else i = 0; endif p = [i, p]; v = sum (d .* p); endfunction