--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/finance/rate.m	Fri Oct 23 05:44:01 1998 +0000
@@ -0,0 +1,72 @@
+## 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
\ No newline at end of file