## [cc7e24]: financial / inst / npv.m  Maximize  Restore  History

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 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69``` ```## Copyright (C) 1995-2000, 2002, 2004-2007 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 3 of the License, 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 program; if not, see . ## -*- texinfo -*- ## @deftypefn {Function File} {} npv (@var{r}, @var{p}, @var{i}) ## Net present value of a series of payments. ## ## 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). ## @seealso{irr, pv} ## @end deftypefn function v = npv (r, p, i) if (nargin < 2 || nargin > 3) print_usage (); 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 ```