/* DEC	*ConvYearlyToPeriodic(peri, yeari, nper);
 *
 * ARGUMENT
 *	DEC	*peri, *yeari;
 *	int	nper;
 *
 * DESCRIPTION
 *	Changes	the interest rate per year to the interest rate	per period.
 *  For	instance, a yearly rate	is changed to a	monthly	rate.
 *  Interest rates should are expressed	as percentages.
 *	yeari is the period rate
 *	nper is	the number of compounding periods.
 *	The resulting periodic rate is store in	peri.
 *
 * SIDE	EFFECTS
 *	none.
 *
 * RETURNS
 *	peri if	successful, otherwise GM_NULL.
 *
 * POSSIBLE ERRORS
 *	GM_NULLPOINTER
 *	GM_ARGVAL
 *
 * AUTHOR
 *  Jared Levy
 *   Copyright (C) 1989-1990 Greenleaf Software	Inc.  All rights reserved.
 *
 * MODIFICATIONS
 *
 *
 */

#include <stdio.h>
#include "gmsystem.h"

DEC	*ConvYearlyToPeriodic(peri, yeari, nper)
DEC	*peri, *yeari;
int	nper;
{
	DEC	dtemp, *temp=&dtemp, ddper, *dper=&ddper;

	_MacStart(GM_YTOP);

	_MacInVarD(yeari);
	_MacOutVarD(peri);

/* nper	must be	>= 1 */
	if ((nper<=0)
		||CompareDecimal(yeari,&decMinusHundred)<=0)  {
		_MacErr(GM_ARGVAL);
		_MacRet(GM_NULL);
	}

/* convert percent to decimal */
	_MacDCopy(temp,	yeari);
	temp->dc.id+=2;

	(void) ConvLongToDecimal(dper, (long) nper);
	(void) _AddDec80Bit(temp, temp,	&decOne);
	(void) _LnDec80Bit(temp, temp);
	(void) _DivDec80Bit(temp, temp,	dper);
	(void) _ExpDec80Bit(temp, temp);
	(void) _SubDec80Bit(temp, temp,	&decOne);

/* convert decimal to percent */
	if (temp->dc.id>=2)
		temp->dc.id-=2;
	else  {
		(void) ConvLongToDecimal(dper, 100L);
		(void) _MulDec80Bit(temp, temp,	dper);
	}

	if ( _Sq5UnsTo4Uns( temp ) != GM_SUCCESS )  {
		_MacErr(GM_ARGVAL);
		_MacRet(GM_NULL);
	}

	_MacDCopy(peri,temp);
	_MacRet(peri);
}