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

Download this file

40 lines (35 with data), 1.4 kB

 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
## Copyright (C) 1995-1998, 2000, 2002, 2004-2007 Kurt Hornik <Kurt.Hornik@wu-wien.ac.at>
##
## 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 <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {} irr (@var{p}, @var{i})
## Return the internal rate of return of a series of payments @var{p}
## from an initial investment @var{i} (i.e., the solution of
## @code{npv (r, p) = i}. If the second argument is omitted, a value of
## 0 is used.
## @seealso{npv, pv, rate}
## @end deftypefn
function r = irr (p, i = 0)
## Check input
if (nargin != 1 && nargin != 2)
print_usage ();
elseif (! (isvector (p)))
error ("irr: p must be a vector");
elseif (! isscalar (i))
error ("irr: i must be a scalar");
endif
## Solve system
f = @(x) npv (x, p) - i;
r = fsolve (f, 0);
endfunction