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
70
71
72
|
## Copyright (C) 1995, 1996, 1997 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.
## usage: rate (n, p, v [, l] [, method])
##
## Computes the rate of return on an investment of present value v which
## pays p in n consecutive periods.
##
## With the optional scalar argument l, one can specify an additional
## lump-sum payment made at the end of n periods. With the optional
## string argument `method', one can specify whether payments are made
## at the end ("e", default) or at the beginning ("b") of each period.
##
## See also: pv, pmt, nper; npv.
## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
## Description: Rate of return of an investment
function r = rate (n, p, v, l, m)
if ((nargin < 3) || (nargin > 5))
usage ("rate (n, p, v [, l] [, method])");
endif
if !(is_scalar (n) && (n > 0))
error ("rate: n must be a positive scalar");
elseif !is_scalar (p)
error ("rate: p must be a scalar");
elseif !is_scalar (v)
error ("rate: p must be a scalar");
endif
if (nargin == 5)
if !isstr (m)
error ("rate: `method' must be a string");
endif
elseif (nargin == 4)
if isstr (l)
m = l;
l = 0;
else
m = "e";
endif
else
l = 0;
m = "e";
endif
if !is_scalar (l)
error ("rate: l must be a scalar");
endif
string = ["function delta = f (r) ", ...
"delta = pv (r, %g, %g, %g, \"%s\") - %g; end"];
eval (sprintf (string, n, p, l, m, v));
[r, info] = fsolve ("f", 0);
endfunction
|
