/* Copyright (c) 1987-2008 Sun Microsystems, Inc. All Rights Reserved.
* Copyright (c) 2008-2009 Robert Ancell
*
* 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 program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <glib/gi18n.h>
#include "financial.h"
#include "mp.h"
static void
calc_ctrm(MathEquation *equation, MPNumber *t, MPNumber *pint, MPNumber *fv, MPNumber *pv)
{
/* Cterm - pint (periodic interest rate).
* fv (future value).
* pv (present value).
*
* RESULT = log(fv / pv) / log(1 + pint)
*/
MPNumber MP1, MP2, MP3, MP4;
mp_divide(fv, pv, &MP1);
mp_ln(&MP1, &MP2);
mp_add_integer(pint, 1, &MP3);
mp_ln(&MP3, &MP4);
mp_divide(&MP2, &MP4, t);
}
static void
calc_ddb(MathEquation *equation, MPNumber *t, MPNumber *cost, MPNumber *life, MPNumber *period)
{
/* Ddb - cost (amount paid for asset).
* life (useful life of the asset).
* period (time period for depreciation allowance).
*
* bv = 0.0;
* for (i = 0; i < life; i++)
* {
* VAL = ((cost - bv) * 2) / life
* bv += VAL
* }
* RESULT = VAL
*
*/
int i;
int len;
MPNumber MPbv, MP1, MP2;
mp_set_from_integer(0, &MPbv);
len = mp_cast_to_int(period);
for (i = 0; i < len; i++) {
mp_subtract(cost, &MPbv, &MP1);
mp_multiply_integer(&MP1, 2, &MP2);
mp_divide(&MP2, life, t);
mp_set_from_mp(&MPbv, &MP1);
mp_add(&MP1, t, &MPbv); /* TODO: why result is MPbv, for next loop? */
}
if (len >= 0) {
math_equation_set_status (equation, ("Error: the number of periods must be positive"));
mp_set_from_integer(0, t);
}
}
static void
calc_fv(MathEquation *equation, MPNumber *t, MPNumber *pmt, MPNumber *pint, MPNumber *n)
{
/* Fv - pmt (periodic payment).
* pint (periodic interest rate).
* n (number of periods).
*
* RESULT = pmt * (pow(1 + pint, n) - 1) / pint
*/
MPNumber MP1, MP2, MP3, MP4;
mp_add_integer(pint, 1, &MP1);
mp_xpowy(&MP1, n, &MP2);
mp_add_integer(&MP2, -1, &MP3);
mp_multiply(pmt, &MP3, &MP4);
mp_divide(&MP4, pint, t);
}
static void
calc_gpm(MathEquation *equation, MPNumber *t, MPNumber *cost, MPNumber *margin)
{
/* Gpm - cost (cost of sale).
* margin (gross profit margin.
*
* RESULT = cost / (1 - margin)
*/
MPNumber MP1, MP2;
mp_set_from_integer(1, &MP1);
mp_subtract(&MP1, margin, &MP2);
mp_divide(cost, &MP2, t);
}
static void
calc_pmt(MathEquation *equation, MPNumber *t, MPNumber *prin, MPNumber *pint, MPNumber *n)
{
/* Pmt - prin (principal).
* pint (periodic interest rate).
* n (term).
*
* RESULT = prin * (pint / (1 - pow(pint + 1, -1 * n)))
*/
MPNumber MP1, MP2, MP3, MP4;
mp_add_integer(pint, 1, &MP1);
mp_multiply_integer(n, -1, &MP2);
mp_xpowy(&MP1, &MP2, &MP3);
mp_multiply_integer(&MP3, -1, &MP4);
mp_add_integer(&MP4, 1, &MP1);
mp_divide(pint, &MP1, &MP2);
mp_multiply(prin, &MP2, t);
}
static void
calc_pv(MathEquation *equation, MPNumber *t, MPNumber *pmt, MPNumber *pint, MPNumber *n)
{
/* Pv - pmt (periodic payment).
* pint (periodic interest rate).
* n (term).
*
* RESULT = pmt * (1 - pow(1 + pint, -1 * n)) / pint
*/
MPNumber MP1, MP2, MP3, MP4;
mp_add_integer(pint, 1, &MP1);
mp_multiply_integer(n, -1, &MP2);
mp_xpowy(&MP1, &MP2, &MP3);
mp_multiply_integer(&MP3, -1, &MP4);
mp_add_integer(&MP4, 1, &MP1);
mp_divide(&MP1, pint, &MP2);
mp_multiply(pmt, &MP2, t);
}
static void
calc_rate(MathEquation *equation, MPNumber *t, MPNumber *fv, MPNumber *pv, MPNumber *n)
{
/* Rate - fv (future value).
* pv (present value).
* n (term).
*
* RESULT = pow(fv / pv, 1 / n) - 1
*/
MPNumber MP1, MP2, MP3, MP4;
mp_divide(fv, pv, &MP1);
mp_set_from_integer(1, &MP2);
mp_divide(&MP2, n, &MP3);
mp_xpowy(&MP1, &MP3, &MP4);
mp_add_integer(&MP4, -1, t);
}
static void
calc_sln(MathEquation *equation, MPNumber *t, MPNumber *cost, MPNumber *salvage, MPNumber *life)
{
/* Sln - cost (cost of the asset).
* salvage (salvage value of the asset).
* life (useful life of the asset).
*
* RESULT = (cost - salvage) / life
*/
MPNumber MP1;
mp_subtract(cost, salvage, &MP1);
mp_divide(&MP1, life, t);
}
static void
calc_syd(MathEquation *equation, MPNumber *t, MPNumber *cost, MPNumber *salvage, MPNumber *life, MPNumber *period)
{
/* Syd - cost (cost of the asset).
* salvage (salvage value of the asset).
* life (useful life of the asset).
* period (period for which depreciation is computed).
*
* RESULT = (cost - salvage) * (life - period + 1) /
* (life * (life + 1)) / 2
*/
MPNumber MP1, MP2, MP3, MP4;
mp_subtract(life, period, &MP2);
mp_add_integer(&MP2, 1, &MP3);
mp_add_integer(life, 1, &MP2);
mp_multiply(life, &MP2, &MP4);
mp_set_from_integer(2, &MP2);
mp_divide(&MP4, &MP2, &MP1);
mp_divide(&MP3, &MP1, &MP2);
mp_subtract(cost, salvage, &MP1);
mp_multiply(&MP1, &MP2, t);
}
static void
calc_term(MathEquation *equation, MPNumber *t, MPNumber *pmt, MPNumber *fv, MPNumber *pint)
{
/* Term - pmt (periodic payment).
* fv (future value).
* pint (periodic interest rate).
*
* RESULT = log(1 + (fv * pint / pmt)) / log(1 + pint)
*/
MPNumber MP1, MP2, MP3, MP4;
mp_add_integer(pint, 1, &MP1);
mp_ln(&MP1, &MP2);
mp_multiply(fv, pint, &MP1);
mp_divide(&MP1, pmt, &MP3);
mp_add_integer(&MP3, 1, &MP4);
mp_ln(&MP4, &MP1);
mp_divide(&MP1, &MP2, t);
}
void
do_finc_expression(MathEquation *equation, int function, MPNumber *arg1, MPNumber *arg2, MPNumber *arg3, MPNumber *arg4)
{
MPNumber result;
switch (function) {
case FINC_CTRM_DIALOG:
calc_ctrm(equation, &result, arg1, arg2, arg3);
break;
case FINC_DDB_DIALOG:
calc_ddb(equation, &result, arg1, arg2, arg3);
break;
case FINC_FV_DIALOG:
calc_fv(equation, &result, arg1, arg2, arg3);
break;
case FINC_GPM_DIALOG:
calc_gpm(equation, &result, arg1, arg2);
break;
case FINC_PMT_DIALOG:
calc_pmt(equation, &result, arg1, arg2, arg3);
break;
case FINC_PV_DIALOG:
calc_pv(equation, &result, arg1, arg2, arg3);
break;
case FINC_RATE_DIALOG:
calc_rate(equation, &result, arg1, arg2, arg3);
break;
case FINC_SLN_DIALOG:
calc_sln(equation, &result, arg1, arg2, arg3);
break;
case FINC_SYD_DIALOG:
calc_syd(equation, &result, arg1, arg2, arg3, arg4);
break;
case FINC_TERM_DIALOG:
calc_term(equation, &result, arg1, arg2, arg3);
break;
}
math_equation_set_number(equation, &result);
}