Source Code 1994 March/Source_Code_CD-ROM_Walnut_Creek_March_1994.iso/compsrcs/misc/volume29/loancalc/part01

Text File | 1992-05-12 | 7.9 KB | 289 lines

Newsgroups: comp.sources.misc
From: [e-mail] (Shel Kaphan)
Subject:  v29i095:  loancalc - a loan calculator, Part01/01
Message-ID: <[e-mail]>
X-Md4-Signature: ceceddd4cc3fe1f1be64a5628ccfc2b5
Date: Mon, 11 May 1992 16:12:33 GMT
Approved: [e-mail]

Submitted-by: [e-mail] (Shel Kaphan)
Posting-number: Volume 29, Issue 95
Archive-name: loancalc/part01
Environment: UNIX

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then feed it
# into a shell via "sh file" or similar.  To overwrite existing files,
# type "sh file -c".
# The tool that generated this appeared in the comp.sources.unix newsgroup;
# send mail to [e-mail] if you want that tool.
# Contents:  loan.c makefile
# Wrapped by kent@sparky on Mon May 11 11:06:50 1992
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
echo If this archive is complete, you will see the following message:
echo '          "shar: End of archive."'
if test -f 'loan.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'loan.c'\"
else
  echo shar: Extracting \"'loan.c'\" \(6047 characters\)
  sed "s/^X//" >'loan.c' <<'END_OF_FILE'
X/*
X  loan.c
X
X  Copyright (C) 1990 by Shel Kaphan    ([e-mail], [e-mail]).
X
X  This program is distributed in the hope that it will be useful,
X  but WITHOUT ANY WARRANTY.  The author accepts no responsibility to anyone
X  for any consequences of using it or for whether it serves any particular
X  purpose or works at all.
X
X  This file may be freely copied, modified, and redistributed,
X  but only so long as this notice is preserved on all copies.
X
X  May be compiled and linked with:
X     gcc -o loan loan.c -lm
X
X*/
X
X
X#include <ctype.h>
X#include <math.h>
X#include <stdio.h>
X
Xint payments_per_year=12;
X
Xfloat expt (num, pow)
X     float num;
X     int pow;
X{
X  float result=1.0;
X  int i;
X  for(i=0; i<pow; i++, result *= num);
X  return result;
X}
X
X
Xvoid show_params(principal, interest_rate, monthly_payment, number_of_payments)
X     float principal;
X     float interest_rate;
X     float monthly_payment;
X     int number_of_payments;
X{
X  float total_interest(float,float,float,int);
X  printf("(P)rincipal          %9.2f\n", principal);
X  printf("(M)onthly payment    %9.2f\n", monthly_payment);
X  printf("(I)nterest rate      %10.3f%%\n", interest_rate*100);
X  printf("(N)umber of payments %6d\n", number_of_payments);
X  printf("\nTotal Interest       %9.2f\n", total_interest(principal,interest_rate,monthly_payment,
X                                                          number_of_payments) );
X
X
X}
X
X
Xfloat total_interest(float principal,float interest_rate,float monthly_payment, int num_payments)
X{
X     int m;
X     float total=0.0;
X     float remaining_principal = principal;
X     for (m=0; m<num_payments; m++) {
X         float monthly_interest = (remaining_principal * interest_rate) / 12;
X         remaining_principal -= (monthly_payment - monthly_interest);
X         total += monthly_interest;
X    }
X    return total;
X}
X
X
X
Xfloat monthly_payment(principal, interest_rate, num_payments)
X     float principal;
X     float interest_rate;
X     int num_payments;
X{
X
X  float monthly_rate = interest_rate / payments_per_year;
X  float monthly_interest = principal * monthly_rate;
X  float compounding_factor = pow((double)(monthly_rate+1.0),
X                 (double)num_payments);
X  float monthly_excess = monthly_interest/(compounding_factor - 1.0);
X  float monthly_payment = monthly_interest+monthly_excess;
X  return monthly_payment;
X
X}
X
Xfloat loan_size(monthly_payment, interest_rate, num_payments)
X     float monthly_payment;
X     float interest_rate;
X     int num_payments;
X{
X  float monthly_rate = interest_rate / payments_per_year;
X  float compounding_factor = pow((double)(monthly_rate+1.0),
X                 (double)num_payments);
X  float monthly_excess = monthly_payment/compounding_factor;
X  float monthly_interest = monthly_payment - monthly_excess;
X  float principal = monthly_interest/monthly_rate;
X  return (principal);
X}
X
Xfloat interest_rate(principal, mon_payment, num_payments)
X     float principal;
X     float mon_payment;
X     int num_payments;
X{
X
X  float guess = (payments_per_year * mon_payment)/principal;
X  float inc = guess * -0.1;
X  float mp;
X  int i;
X  for(i=0; i<1000; i++) {
X    mp = monthly_payment(principal, guess, num_payments);
X/*    printf("guess = %f    estimate = %.2f\n", guess, mp); */
X    if (fabs(mp - mon_payment) <= .005) return guess;
X    if (mp-mon_payment > 0) {
X      if (inc > 0) inc = inc * -0.5;
X    } else {
X      if (inc < 0) inc = inc * -0.5;
X    }
X    guess += inc;
X
X    if (guess <=0) {
X      guess -= inc;
X      guess *= .05;
X    }
X
X  }
X
X  printf("\n*** This is getting nowhere! Try something more realistic... ***\n\n");
X
X  return 0.0;
X}
X
X
Xint number_of_payments(principal, monthly_payment, interest_rate)
X     float principal;
X     float monthly_payment;
X     float interest_rate;
X{
X  float compounding_factor;
X  int num_payments;
X
X  float monthly_rate = interest_rate / payments_per_year;
X  float monthly_interest = monthly_rate * principal;
X  float monthly_excess = monthly_payment - monthly_interest;
X  if (monthly_excess<=0.0) {
X    printf("\n*** THIS LOAN CAN NEVER BE PAID OFF AT THIS INTEREST RATE ***\n\n");
X    return 0;
X  }
X  compounding_factor = monthly_payment / monthly_excess;
X  num_payments = (int) ceil(log((double)compounding_factor) /
X               log((double)(1.0 + monthly_rate)));
X  return num_payments;
X}
X
X
Xvoid command_loop() {
X  char command;
X  float arg1, arg2, arg3;
X  int matches;
X  float int_rate = .10;
X  float principal = 100000;
X  int num_payments = 360;
X  float mon_payment = 877.58;
X  char cbuf[100];
X
X  printf("Type '?' for help\n");
X  while(1) {
X    printf("> ");
X    if (gets(cbuf)==NULL) return;
X    matches = sscanf(cbuf, " %c %f %f %f ", &command, &arg1, &arg2, &arg3);
X    if (matches<=0) continue;
X
X    if (isupper(command)) command = tolower(command);
X
X    switch(command) {
X    case 'i':            /* set interest rate */
X      if (matches>=2) {
X    int_rate = arg1;
X    if (int_rate >= 1.0) int_rate *= .01;
X      } else
X    int_rate = interest_rate(principal, mon_payment, num_payments);
X
X      break;
X    case 'p':            /* set principal */
X      if (matches>=2) {
X    principal = arg1;
X      } else
X    principal = loan_size(mon_payment, int_rate, num_payments);
X      break;
X    case 'n':            /* set number of payments */
X      if (matches>=2) {
X    num_payments = (int)ceil((double)arg1);
X      } else {
X    int n = number_of_payments(principal, mon_payment, int_rate);
X    if (n)
X      num_payments=n;
X    else
X      matches=0;
X      }
X      break;
X    case 'm':            /* set monthly payment */
X      if (matches>=2) {
X    mon_payment = arg1;
X      }  else
X    mon_payment = monthly_payment(principal, int_rate, num_payments);
X      break;
X    case 'q':
X      exit(0);
X    case '?':
X    case 'h':
X      printf("Type 'p', 'm', 'i', or 'n' followed by a number to set the Principal,\n\
XMonthly payment, Interest rate, or Number of payments, respectively.\n\
XThe same commands with no arguments recalculate the specified quantity.\n\
XType q to quit.\n\n");
X      matches=0;
X      break;
X    default:
X      printf("Huh?\n");
X      matches=0;
X      break;
X    }
X
X    if (matches==1)
X      show_params(principal, int_rate, mon_payment, num_payments);
X
X  }
X
X}
X
X
X
Xmain () {
X  command_loop();
X}
X
END_OF_FILE
  if test 6047 -ne `wc -c <'loan.c'`; then
    echo shar: \"'loan.c'\" unpacked with wrong size!
  fi
  # end of 'loan.c'
fi
if test -f 'makefile' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'makefile'\"
else
  echo shar: Extracting \"'makefile'\" \(40 characters\)
  sed "s/^X//" >'makefile' <<'END_OF_FILE'
XCC=gcc
X
Xloan:
X    ${CC} -o loan loan.c -lm
END_OF_FILE
  if test 40 -ne `wc -c <'makefile'`; then
    echo shar: \"'makefile'\" unpacked with wrong size!
  fi
  # end of 'makefile'
fi
echo shar: End of archive.
exit 0
exit 0 # Just in case...