691 lines
20 KiB
C
691 lines
20 KiB
C
/*
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* $Id$
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*/
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/*
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* Harbour Project source code:
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* CT3 Financial functions
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* - PV
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* - FV
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* - PAYMENT
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* - PERIODS
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* - RATE
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*
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* NOTE: All these functions were builded using Borland C++ 5.5 (free version)
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*
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* Copyright 2001 Alejandro de Garate <alex_degarate@hotmail.com>
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*
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* Documentation and changes concerning error handling Copyright 2001
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* IntTec GmbH, Freiburg, Germany, Author: Martin Vogel <vogel@inttec.de>
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*
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* www - http://www.harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
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*
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* As a special exception, the Harbour Project gives permission for
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* additional uses of the text contained in its release of Harbour.
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*
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* The exception is that, if you link the Harbour libraries with other
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* files to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the Harbour library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the Harbour
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* Project under the name Harbour. If you copy code from other
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* Harbour Project or Free Software Foundation releases into a copy of
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* Harbour, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for Harbour, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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*
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*/
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#include "ct.h"
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/* $DOC$
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* $FUNCNAME$
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* FV()
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* $CATEGORY$
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* CT3 math functions
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* $ONELINER$
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* Future value of a capital
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* $SYNTAX$
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* FV (nDeposit, nInterest, nPeriods) --> nFutureValue
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* $ARGUMENTS$
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* <nDeposit> amount of money invested per period
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* <nInterest> rate of interest per period, 1 == 100%
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* <nPeriods> period count
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* $RETURNS$
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* <nFutureValue> Total value of the capital after <nPeriods> of
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* paying <nDeposit> and <nInterest> interest being
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* paid every period and added to the capital (resulting
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* in compound interest)
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* $DESCRIPTION$
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* FV() calculates the value of a capital after <nPeriods> periods.
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* Starting with a value of 0, every period, <nDeposit>
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* (Dollars, Euros, Yens, ...) and an interest of <nInterest> for the
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* current capital are added for the capital (<nInterest>=Percent/100).
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* Thus, one gets the non-linear effects of compound interests:
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* value in period 0 = 0
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* value in period 1 = ((value in period 0)*(1+<nInterest>/100)) + <nDeposit>
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* value in period 2 = ((value in period 1)*(1+<nInterest>/100)) + <nDeposit>
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* etc....
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* value in period <nPeriod> = ((value in period <nPeriod>-1)*(1+<nInterest>/100))< + <nDeposit>
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* = <nDeposit> * sum from i=0 to <nPeriod>-1 over (1+<nInterest>/100)^i
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* = <nDeposit> * ((1+<nInterest>/100)^n-1) / (<nInterest>/100)
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* $EXAMPLES$
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* // Payment of 1000 per year for 10 years at a interest rate
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* // of 5 per cent per year
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*
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* ? fv (1000, 0.05, 10) --> 12577.893
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* $TESTS$
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* fv (1000, 0.00, 10) == 10000.0
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* fv (1000, 0.05, 10) == 12577.893
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* $STATUS$
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* Ready
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* $COMPLIANCE$
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* FV() is compatible with CT3's FV().
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* $PLATFORMS$
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* All
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* $FILES$
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* Source is finan.c, library is libct.
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* $SEEALSO$
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* PV(),PAYMENT(),PERIODS(),RATE()
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* $END$
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*/
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HB_FUNC( FV )
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{
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if( ISNUM(1) && ISNUM(2) && ISNUM(3) )
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{
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double dPayment = hb_parnd(1);
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double dRate = hb_parnd(2);
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double dTime = hb_parnd(3);
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double dResult;
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if (dRate == 0.0)
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{
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/* NOTE: CT3 crashes with dRate == 0.0 */
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dResult = dPayment*dTime;
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}
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else
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{
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hb_mathResetError();
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dResult = dPayment*(pow (1.0+dRate, dTime)-1.0)/dRate;
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if (hb_mathIsMathErr())
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{
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/* the C-RTL provides a kind of matherr() mechanism */
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HB_MATH_EXCEPTION hb_exc;
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int iLastError = hb_mathGetLastError (&hb_exc);
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if (iLastError != HB_MATH_ERR_NONE)
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{
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if (hb_exc.handled)
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{
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hb_retnd (dPayment*(hb_exc.retval-1.0)/dRate);
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}
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else
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{
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/* math exception is up to the Harbour function, so do this as CTIII compatible as possible:
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replace the errorneous value of pow() with 0.0 */
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hb_retnd (dPayment*(-1.0)/dRate);
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}
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return;
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}
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}
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}
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hb_retnd (dResult);
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}
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else
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{
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PHB_ITEM pSubst = NULL;
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int iArgErrorMode = ct_getargerrormode();
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if (iArgErrorMode != CT_ARGERR_IGNORE)
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{
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pSubst = ct_error_subst ((USHORT)iArgErrorMode, EG_ARG, CT_ERROR_FV,
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NULL, "FV", 0, EF_CANSUBSTITUTE, 3,
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hb_paramError (1), hb_paramError (2),
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hb_paramError (3));
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}
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if (pSubst != NULL)
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{
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hb_itemReturn (pSubst);
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hb_itemRelease (pSubst);
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}
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else
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{
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hb_retnd (0.0);
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}
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}
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return;
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}
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/* $DOC$
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* $FUNCNAME$
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* PV()
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* $CATEGORY$
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* CT3 math functions
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* $ONELINER$
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* Present value of a loan
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* $SYNTAX$
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* PV (nPayment, nInterest, nPeriods) --> nPresentValue
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* $ARGUMENTS$
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* <nPayment> amount of money paid back per period
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* <nInterest> rate of interest per period, 1 == 100%
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* <nPeriods> period count
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* $RETURNS$
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* <nPresentValue> Present value of a loan when one is paying back
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* <nDeposit> per period at a rate of interest of
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* <nInterest> per period
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* $DESCRIPTION$
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* PV() calculates the present value of a loan that is paid back
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* in <nPeriods> payments of <nPayment> (Dollars, Euros, Yens,...)
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* while the rate of interest is <nInterest> per period:
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* debt in period 0 = <nPresentValue>
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* debt in period 1 = ((debt in period 0)-<nPayment>)*(1+<nInterest>/100)
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* debt in period 2 = ((debt in period 1)-<nPayment>)*(1+<nInterest>/100)
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* etc...
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* debt in period <nPeriod> = ((debt in period <nPeriod>-1)-<nPayment>)*(1+<nInterest>/100)
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* -> has to be 0, so
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* <nPresentValue> = <nPayment>*(1-(1+<nInterest>/100)^(-n))/(<nInterest>/100)
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* $EXAMPLES$
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* // You can afford to pay back 100 Dollars per month for 5 years
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* // at a interest rate of 0.5% per month (6% per year), so instead
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* // of 6000 Dollars (the amount you will pay back) the bank will pay
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* // you
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*
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* ? pv (100, 0.005, 60) --> 5172.56
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* $TESTS$
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* pv (100, 0.0, 60) == 6000.0
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* pv (100, 0.005, 60) == 5172.56
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* $STATUS$
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* Ready
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* $COMPLIANCE$
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* PV() is compatible with CT3's PV().
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* $PLATFORMS$
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* All
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* $FILES$
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* Source is finan.c, library is libct.
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* $SEEALSO$
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* FV(),PAYMENT(),PERIODS(),RATE()
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* $END$
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*/
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HB_FUNC( PV )
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{
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if( ISNUM(1) && ISNUM(2) && ISNUM(3) )
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{
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double dPayment = hb_parnd(1);
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double dRate = hb_parnd(2);
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double dTime = hb_parnd(3);
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double dResult;
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if (dRate == 0.0)
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{
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/* NOTE: CT3 crashes with dRate == 0.0 */
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dResult = dPayment*dTime;
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}
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else
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{
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hb_mathResetError();
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dResult = dPayment*(1.0-pow (1.0+dRate, -dTime))/dRate;
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if (hb_mathIsMathErr())
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{
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/* the C-RTL provides a kind of matherr() mechanism */
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HB_MATH_EXCEPTION hb_exc;
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int iLastError = hb_mathGetLastError (&hb_exc);
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if (iLastError != HB_MATH_ERR_NONE)
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{
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if (hb_exc.handled)
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{
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hb_retnd (dPayment*(1.0-hb_exc.retval)/dRate);
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}
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else
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{
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/* math exception is up to the Harbour function, so do this as CTIII compatible as possible:
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replace the errorneous value of pow() with 0.0 */
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hb_retnd (dPayment/dRate);
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}
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return;
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}
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}
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}
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hb_retnd (dResult);
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}
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else
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{
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PHB_ITEM pSubst = NULL;
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int iArgErrorMode = ct_getargerrormode();
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if (iArgErrorMode != CT_ARGERR_IGNORE)
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{
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pSubst = ct_error_subst ((USHORT)iArgErrorMode, EG_ARG, CT_ERROR_PV,
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NULL, "PV", 0, EF_CANSUBSTITUTE, 3,
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hb_paramError (1), hb_paramError (2),
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hb_paramError (3));
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}
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if (pSubst != NULL)
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{
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hb_itemReturn (pSubst);
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hb_itemRelease (pSubst);
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}
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else
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{
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hb_retnd (0.0);
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}
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}
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return;
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}
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/* $DOC$
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* $FUNCNAME$
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* PAYMENT()
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* $CATEGORY$
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* CT3 math functions
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* $ONELINER$
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* Payments for a loan
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* $SYNTAX$
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* PAYMENT (nLoan, nInterest, nPeriods) --> nPayment
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* $ARGUMENTS$
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* <nLoan> amount of money you get from the bank
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* <nInterest> rate of interest per period, 1 == 100%
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* <nPeriods> period count
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* $RETURNS$
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* <nPayment> Periodical payment one has to make to pay the
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* loan <nLoan> back
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* $DESCRIPTION$
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* PAYMENT() calculates the payment one has to make periodically
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* to pay back a loan <nLoan> within <nPeriods> periods and for a
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* rate of interest <nInterest> per period.
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* debt in period 0 = <nLoan>
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* debt in period 1 = ((debt in period 0)-<nPayment>)*(1+<nInterest>/100)
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* debt in period 2 = ((debt in period 1)-<nPayment>)*(1+<nInterest>/100)
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* etc...
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* debt in period <nPeriod> = ((debt in period <nPeriod>-1)-<nPayment>)*(1+<nInterest>/100)
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* -> has to be 0, so
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* <nPayment> = <nLoan>*(<nInterest>/100)/(1-(1+<nInterest>/100)^(-n))
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* $EXAMPLES$
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* // You get a loan of 5172.56 at a interest rate of 0.5% per
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* // month (6% per year).
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* // For 5 years, you have to pay back every month
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*
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* ? payment (5172.56, 0.005, 60) --> 100.00
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* $TESTS$
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* payment (5172.56, 0.0, 60) == 86.21
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* payment (5172.56, 0.005, 60) == 100.00
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* $STATUS$
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* Ready
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* $COMPLIANCE$
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* PAYMENT() is compatible with CT3's PAYMENT().
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* $PLATFORMS$
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* All
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* $FILES$
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* Source is finan.c, library is libct.
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* $SEEALSO$
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* PV(),FV(),PERIODS(),RATE()
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* $END$
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*/
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HB_FUNC( PAYMENT )
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{
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if( ISNUM(1) && ISNUM(2) && ISNUM(3) )
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{
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double dCapital = hb_parnd(1);
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double dRate = hb_parnd(2);
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double dTime = hb_parnd(3);
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double dResult;
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if (dRate == 0.0)
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{
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/* NOTE: CT3 crashes with dRate == 0.0 */
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dResult = dCapital/dTime;
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}
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else
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{
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hb_mathResetError();
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dResult = dCapital*dRate/(1.0-pow (1.0+dRate, -dTime));
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if (hb_mathIsMathErr())
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{
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/* the C-RTL provides a kind of matherr() mechanism */
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HB_MATH_EXCEPTION hb_exc;
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int iLastError = hb_mathGetLastError (&hb_exc);
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if (iLastError != HB_MATH_ERR_NONE)
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{
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if (hb_exc.handled)
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{
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hb_retnd (dCapital*dRate/(1.0-hb_exc.retval));
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}
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else
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{
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/* math exception is up to the Harbour function, so do this as CTIII compatible as possible:
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replace the errorneous value of pow() with 0.0 */
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hb_retnd (dCapital*dRate);
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}
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return;
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}
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}
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}
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hb_retnd (dResult);
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}
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else
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{
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PHB_ITEM pSubst = NULL;
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int iArgErrorMode = ct_getargerrormode();
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if (iArgErrorMode != CT_ARGERR_IGNORE)
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{
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pSubst = ct_error_subst ((USHORT)iArgErrorMode, EG_ARG, CT_ERROR_PAYMENT,
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NULL, "PAYMENT", 0, EF_CANSUBSTITUTE, 3,
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hb_paramError (1), hb_paramError (2),
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hb_paramError (3));
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}
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if (pSubst != NULL)
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{
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hb_itemReturn (pSubst);
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hb_itemRelease (pSubst);
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}
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else
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{
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hb_retnd (0.0);
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}
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}
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return;
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}
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/* $DOC$
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* $FUNCNAME$
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* PERIODS()
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* $CATEGORY$
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* CT3 math functions
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* $ONELINER$
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* Number of periods for a loan
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* $SYNTAX$
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* PERIODS (nLoan, nPayment, nInterest) --> nPeriods
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* $ARGUMENTS$
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* <nLoan> amount of money you get from the bank
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* <nPayment> amount of money you pay back per period
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* <nInterest> rate of interest per period, 1 == 100%
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* $RETURNS$
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* <nPeriods> number of periods you need to pay the loan back
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* $DESCRIPTION$
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* PERIODS() calculates the number of periods one needs to pay back
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* a loan of <nLoan> with periodical payments of <nPayment> and for a
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* rate of interest <nInterest> per period.
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* debt in period 0 = <nLoan>
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* debt in period 1 = ((debt in period 0)-<nPayment>)*(1+<nInterest>/100)
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* debt in period 2 = ((debt in period 1)-<nPayment>)*(1+<nInterest>/100)
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* etc...
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* debt in period <nPeriod> = ((debt in period <nPeriod>-1)-<nPayment>)*(1+<nInterest>/100)
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* -> has to be 0, so
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* <nPeriods> = -log(1-<nLoan>*(<nInterest>/100)/<nPayment>)/log(1+<nInterest>/100))
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*
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* Note, however that in the case of nPayment <= <nLoan>*(<nInterest>/100),
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* one would need infinite time to pay the loan back. The functions does
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* then return -1.
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* $EXAMPLES$
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* // You get a loan of 5172.56 at a interest rate of 0.5% per
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* // month (6% per year).
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* // You can afford to pay 100 back every month, so you need
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*
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* ? periods (5172.56, 100, 0.005) --> 60.0
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*
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* // months to cancel the loan.
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* $TESTS$
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* periods (5172.56, 100, 0.005) == 60.0
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* periods (5172.56, 100, 0.0) == 51.7256
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* $STATUS$
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* Ready
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* $COMPLIANCE$
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* PERIODS() is compatible with CT3's PERIODS().
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* $PLATFORMS$
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* All
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* $FILES$
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* Source is finan.c, library is libct.
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* $SEEALSO$
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* PV(),FV(),PAYMENT(),RATE()
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* $END$
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*/
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HB_FUNC( PERIODS )
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{
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if( ISNUM(1) && ISNUM(2) && ISNUM(3) )
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{
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double dCapital = hb_parnd(1);
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double dPayment = hb_parnd(2);
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double dRate = hb_parnd(3);
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double dResult;
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if (dPayment <= dCapital*dRate)
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{
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/* in this case infinite time is needed to cancel the loan */
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hb_retnd (-1.0);
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return;
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}
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if (dRate == 0.0)
|
|
{
|
|
/* NOTE: CT3 crashes with dRate == 0.0 */
|
|
dResult = dCapital/dPayment;
|
|
}
|
|
else
|
|
{
|
|
double dResult2;
|
|
hb_mathResetError();
|
|
/* Note that this first expression will never give an error since dCapital*dRate/dPayment < 1.0, see above */
|
|
dResult2 = -log(1.0-(dCapital*dRate/dPayment));
|
|
dResult = dResult2/log(1+dRate);
|
|
if (hb_mathIsMathErr())
|
|
{
|
|
/* the C-RTL provides a kind of matherr() mechanism */
|
|
HB_MATH_EXCEPTION hb_exc;
|
|
int iLastError = hb_mathGetLastError (&hb_exc);
|
|
if (iLastError != HB_MATH_ERR_NONE)
|
|
{
|
|
if (hb_exc.handled)
|
|
{
|
|
hb_retnd (dResult2/hb_exc.retval);
|
|
}
|
|
else
|
|
{
|
|
/* math exception is up to the Harbour function, so do this as CTIII compatible as possible:
|
|
replace the errorneous value of log() with -INF */
|
|
hb_retnd (-0.0);
|
|
}
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
hb_retnd( dResult );
|
|
}
|
|
else
|
|
{
|
|
PHB_ITEM pSubst = NULL;
|
|
int iArgErrorMode = ct_getargerrormode();
|
|
if (iArgErrorMode != CT_ARGERR_IGNORE)
|
|
{
|
|
pSubst = ct_error_subst ((USHORT)iArgErrorMode, EG_ARG, CT_ERROR_PERIODS,
|
|
NULL, "PERIODS", 0, EF_CANSUBSTITUTE, 3,
|
|
hb_paramError (1), hb_paramError (2),
|
|
hb_paramError (3));
|
|
}
|
|
|
|
if (pSubst != NULL)
|
|
{
|
|
hb_itemReturn (pSubst);
|
|
hb_itemRelease (pSubst);
|
|
}
|
|
else
|
|
{
|
|
hb_retnd (0.0);
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
|
|
/* $DOC$
|
|
* $FUNCNAME$
|
|
* RATE()
|
|
* $CATEGORY$
|
|
* CT3 math functions
|
|
* $ONELINER$
|
|
* Estimate rate of interest for a loan
|
|
* $SYNTAX$
|
|
* RATE (nLoan, nPayment, nPeriods) --> nRate
|
|
* $ARGUMENTS$
|
|
* <nLoan> amount of money you get from the bank
|
|
* <nPayment> amount of money you pay back per period
|
|
* <nPeriods> number of periods you pay the loan back
|
|
* $RETURNS$
|
|
* <nInterest> estimated rate of interest per period, 1 == 100%
|
|
* $DESCRIPTION$
|
|
* RATE() calculates the rate of interest per period for the given
|
|
* loan, payment per periods and number of periods. This is done with
|
|
* the same equation used in the PAYMENT() or PERIODS() function:
|
|
*
|
|
* <nPayment> = <nLoan>*(<nInterest>/100)/(1-(1+<nInterest>/100)^(-<nPeriods>))
|
|
*
|
|
* However, this equation can not be solved for <nInterest> in a "closed"
|
|
* manner, i.e. <nInterest> = ..., so that the result can only be estimated.
|
|
* $EXAMPLES$
|
|
* // You get a loan of 5172.56, pay 100 back every month for
|
|
* // 5 years (60 months). The effective interest rate per
|
|
* // period (=month) is
|
|
*
|
|
* ? rate (5172.56, 100, 60) --> 0.005
|
|
*
|
|
* $TESTS$
|
|
* rate (5172.56, 100, 60.0) == 0.005
|
|
* rate (6000.0, 100, 60.0) == 0.0
|
|
* $STATUS$
|
|
* Ready
|
|
* $COMPLIANCE$
|
|
* RATE() is compatible with CT3's RATE().
|
|
* $PLATFORMS$
|
|
* All
|
|
* $FILES$
|
|
* Source is finan.c, library is libct.
|
|
* $SEEALSO$
|
|
* PV(),FV(),PAYMENT(),PERIODS()
|
|
* $END$
|
|
*/
|
|
|
|
HB_FUNC( RATE )
|
|
{
|
|
if( ISNUM(1) && ISNUM(2) && ISNUM(3) )
|
|
{
|
|
double dCapital = hb_parnd(1);
|
|
double dPayment = hb_parnd(2);
|
|
double dTime = hb_parnd(3);
|
|
double dAux; /* estimated payment to compare for */
|
|
double dEpsilon = 0.00001; /* mimimal to consider 2 numbers as equal*/
|
|
double dScale = 1.0; /* fractional step */
|
|
double r; /* temptative rate */
|
|
double j = 1.0; /* index */
|
|
double dExp;
|
|
|
|
while( j < 1020.0 ) /* maximum anual rate */
|
|
{
|
|
r = j * 0.000833333; /* j * ( 0.01 / 12.0) mensual's rate */
|
|
|
|
/* replace PAYMENT() function overhead */
|
|
hb_mathResetError();
|
|
dExp = pow( (1.0 + r), dTime );
|
|
if (hb_mathIsMathErr())
|
|
{
|
|
/* the C-RTL provides a kind of matherr() mechanism */
|
|
HB_MATH_EXCEPTION hb_exc;
|
|
int iLastError = hb_mathGetLastError (&hb_exc);
|
|
if (iLastError != HB_MATH_ERR_NONE)
|
|
{
|
|
if (hb_exc.handled)
|
|
{
|
|
dExp = hb_exc.retval;
|
|
}
|
|
else
|
|
{
|
|
/* TODO: Check if this is a correct default correction value for pow() */
|
|
dExp = 0.0;
|
|
}
|
|
}
|
|
}
|
|
|
|
dAux = dCapital * ( (dExp * r) / (dExp - 1.0) );
|
|
|
|
if( dAux > dPayment )
|
|
{
|
|
j = j - dScale;
|
|
dScale = dScale * 0.10;
|
|
|
|
if( (dAux - dPayment) < dEpsilon)
|
|
break;
|
|
}
|
|
else
|
|
j = j + dScale;
|
|
|
|
} /* endwhile */
|
|
|
|
hb_retnd( j * 0.000833333 ); /* return as mensual's rate */
|
|
}
|
|
else
|
|
{
|
|
PHB_ITEM pSubst = NULL;
|
|
int iArgErrorMode = ct_getargerrormode();
|
|
if (iArgErrorMode != CT_ARGERR_IGNORE)
|
|
{
|
|
pSubst = ct_error_subst ((USHORT)iArgErrorMode, EG_ARG, CT_ERROR_RATE,
|
|
NULL, "RATE", 0, EF_CANSUBSTITUTE, 3,
|
|
hb_paramError (1), hb_paramError (2),
|
|
hb_paramError (3));
|
|
}
|
|
|
|
if (pSubst != NULL)
|
|
{
|
|
hb_itemReturn (pSubst);
|
|
hb_itemRelease (pSubst);
|
|
}
|
|
else
|
|
{
|
|
hb_retnd (0.0);
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
|
|
|