101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
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/* void Amortize(payintr,payprin,balance,intr,pv,pmt,begend,time)
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*
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* ARGUMENT
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* DEC *payintr,*payprin,*balance;
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* DEC *intr, *pv, *pmt;
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* int begend, time;
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*
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* DESCRIPTION
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* For a certain payment of a loan, computes the amount of the payment
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* applied towards interest (payintr), the amount of the payment applied
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* towards principle (payprin), and the remaining balance (balance). The
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* loan is described by its present value (pv), the payment (pmt), the
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* interest rate (intr), and whether payments are at the beginning or end
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* of the month (begend), while time tells the payment for which the
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* calculations should be done. pv should be positive while pmt should be
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* negative to obey the sign convention. The output is rounded to two
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* decimal places.
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*
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* SIDE EFFECTS
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* None.
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*
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* RETURNS
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* None.
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*
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* POSSIBLE ERRORS
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* GM_NULLPOINTER
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* GM_ARGVAL
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*
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* AUTHOR
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* Jared Levy
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* Copyright (C) 1988-1990 Greenleaf Software Inc. All rights reserved.
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*
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* MODIFICATIONS
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*
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*
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*/
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#include <stdio.h>
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#include "gm.h"
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#include "gmsystem.h"
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void Amortize(payintr,payprin,balance,intr,pv,pmt,begend,time)
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DEC *payintr,*payprin,*balance;
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DEC *intr, *pv, *pmt;
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int begend, time;
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{
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int i;
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DEC dnintr, *nintr=&dnintr, dnpmt, *npmt=&dnpmt;
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_MacStart(GM_AMORT);
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if (!payintr||!payprin||!balance||!intr||!pv||!pmt) {
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_MacErr(GM_NULLPOINTER);
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_MacRetV;
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}
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if (_MacBad(intr) || _MacBad(pv) || _MacBad(pmt)) {
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_MacErr(GM_INIT);
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_MacRetV;
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}
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if ((begend!=GM_BEGIN&&begend!=GM_END)||time<0) {
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_MacErr(GM_ARGVAL);
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_MacRetV;
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}
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_MacDCopy(nintr, intr);
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nintr->dc.id+=2;
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_ScaleDec80Bit(npmt,pmt,2);
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/* store results for payment '0' */
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_MacDZero(payintr);
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_MacDZero(payprin);
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(void) _ScaleDec80Bit(balance,pv,2);
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if (time==0)
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_MacRetV;
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/* calculate payment 1 results */
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if (begend!=GM_BEGIN) {
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(void) _MulDec80Bit(payintr, balance, nintr);
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(void) _ScaleDec80Bit(payintr, payintr ,2);
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if (_MacIsDecN(payintr)^_MacIsDecN(npmt))
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_MacDChgs(payintr);
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}
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(void) _SubDec80Bit(payprin, npmt, payintr);
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(void) _SubDec80Bit(balance, balance, payprin);
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/* calculate rest of payments */
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for (i=2;i<=time;i++) {
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(void) _MulDec80Bit(payintr, balance, nintr);
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(void) _ScaleDec80Bit(payintr,payintr,2);
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if (_MacIsDecN(payintr)^_MacIsDecN(npmt))
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_MacDChgs(payintr);
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(void) _SubDec80Bit(payprin, npmt, payintr);
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(void) _SubDec80Bit(balance, balance, payprin);
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}
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_MacRetV;
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}
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