#!/bin/bash
# monthlypmt.sh: Àú´ç¿¡ ´ëÇÑ ¿ù »óȯ¾×À» °è»ê.


# ÀÌ ½ºÅ©¸³Æ®´Â Jeff Schmidt ¿Í Mendel Cooper(ÀÌ ¹®¼­ÀÇ ÀúÀÚÀÎ º»ÀÎ)ÀÌ ÀÛ¼ºÇÑ
# "mcalc"(Àú´ç¾× °è»ê±â, mortgage calculator) ÆÐÅ°ÁöÀÇ ¼öÁ¤º»ÀÔ´Ï´Ù.
#   http://www.ibiblio.org/pub/Linux/apps/financial/mcalc-1.6.tar.gz  [15k]

echo
echo "¿ø±Ý, ÀÌÀÚÀ², Àú´ç ±â°£À» ÀÔ·ÂÇÏ¸é ¿ù »óȯ¾×À» °è»êÇÕ´Ï´Ù."

bottom=1.0

echo
echo -n "¿ø±ÝÀ» ³ÖÀ¸¼¼¿ä(ÄÞ¸¶ ¾øÀÌ) "
read principal
echo -n "ÀÌÀÚÀ²À» ³ÖÀ¸¼¼¿ä(ÆÛ¼¾Æ®·Î) "  # ¸¸¾à¿¡ 12% ¶ó¸é ".12"°¡ ¾Æ´Ï°í "12"¶ó°í ÀÔ·Â.
read interest_r
echo -n "±â°£À» ³ÖÀ¸¼¼¿ä(¿ù ´ÜÀ§) "
read term


 interest_r=$(echo "scale=9; $interest_r/100.0" | bc) # ¼Ò¼ö·Î º¯È¯.
                 # "scale" ·Î ¼Ò¼öÁ¡ ÀÌÇÏ ¸î ÀÚ¸®±îÁö Ç¥ÇöÇÒ °ÍÀÎÁö¸¦ °áÁ¤.
  

 interest_rate=$(echo "scale=9; $interest_r/12 + 1.0" | bc)
 

 top=$(echo "scale=9; $principal*$interest_rate^$term" | bc)

 echo; echo "½Ã°£ÀÌ Á» °É¸®¹Ç·Î, ´À±ßÇÏ°Ô ±â´Ù¸®±â ¹Ù¶ø´Ï´Ù."

 let "months = $term - 1"
 for ((x=$months; x > 0; x--))
 do
   bot=$(echo "scale=9; $interest_rate^$x" | bc)
   bottom=$(echo "scale=9; $bottom+$bot" | bc)
#  bottom = $(($bottom + $bot"))
 done

 # let "payment = $top/$bottom"
 payment=$(echo "scale=2; $top/$bottom" | bc)
 # ´Þ·¯¿Í ¼¾Æ® Ç¥½Ã¸¦ À§ÇØ ¼Ò¼öÁ¡ ÀÌÇÏ µÎ ÀÚ¸®¸¸ Ç¥½Ã.
 
 echo
 echo "¿ù »óȯ¾× = \$$payment"  # °á°ú ¾Õ¿¡ ´Þ·¯ Ç¥½Ã¸¦ ¿¡ÄÚ.
 echo


 exit 0

 # ¿¬½À¹®Á¦:
 #   1) ¿ø±Ý ÀԷ½à ÄÞ¸¶¸¦ ¾µ ¼ö ÀÖ°Ô ÇØ º¸¼¼¿ä.
 #   2) ÀÌÀÚ ÀԷ½à ÆÛ¼¾Æ® Ç¥½Ã³ª ¼Ò¼öÁ¡ Ç¥½Ã µÑ ´Ù ¾µ ¼ö ÀÖ°Ô ÇØ º¸¼¼¿ä.
 #   3) ´õ ¸ÚÀÖ´Â ½ºÅ©¸³Æ®·Î ¸¸µé·Á¸é,
 #      ¿ÏÀüÇÑ ºÎä »óȯǥ(amortization tables)¸¦ Ãâ·ÂÇϵµ·Ï °íÃÄ º¸¼¼¿ä.