## Money exchange program for BatMUD | ||

## 0. Contents
## 1. Purpose
I do not have access to the BatMUD shopkeeper money exchange
algorithm file, so I wrote my own.
Shortly: It even handles the cases when you don't have enough money (no it does not walk to Bank), or you have no suitable coins. ## 2. BatMUD coins and relative values
mithril=500, batium=100, anipium=50, platinum=10, gold=1,
silver=0.6, bronze=0.4, copper=0.2, tin=0.1, zinc=0.05, mowgles=0.01
## 3. Examples
Here are some examples of running this program.
## 3.1. Being richYou are carrying 20.0 kg of equipment: 4049 coins (402 mithril, 91 batium, 69 anipium, 53 platinum, 1155 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 361 zinc and 1200 mowgles) [Cash: 21555 Bank: 1 Total: 215516] And you want to pay Bisqwit 3134.39 gold from what you're carrying. ## 3.1.1. Being penny-wise
Fine. You do this:
./batmoney bisqwit 3134.39and the you copypaste your money possessions to the program. The program calculates what you should do: *** Now paste your inventory here (the lines saying what coins do you have): *** Thank you *** Inv at start: 402 mithril, 91 batium, 69 anipium, 53 platinum, 1155 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 361 zinc, 1200 mowgles, that is 215515.45... *** first: gave 1200 mowgles... so I've 3122.39 left to pay. *** first: gave 361 zinc... so I've 3104.34 left to pay. *** first: gave 212 tin... so I've 3083.14 left to pay. *** first: gave 133 copper... so I've 3056.54 left to pay. *** first: gave 106 bronze... so I've 3014.14 left to pay. *** first: gave 267 silver... so I've 2853.94 left to pay. *** first: gave 1155 gold... so I've 1698.94 left to pay. *** first: gave 53 platinum... so I've 1168.94 left to pay. *** first: gave 23 anipium... so I've 18.94 left to pay. *** Inv now: 402 mithril, 91 batium, 46 anipium, that is 212400.00... *** Have gave: 23 anipium, 53 platinum, 1155 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 361 zinc, 1200 mowgles, that is 3115.45... *** exchange: gave 1 anipium (50.00), now I want 31.06 back... *** exchange: took back 3 platinum (30.00)... *** exchange: took back 1 gold (1.00)... *** exchange: took back 1 zinc (0.05)... *** exchange: took back 1 mowgles (0.01)... ----------- *** Inv now: 402 mithril, 91 batium, 45 anipium, 3 platinum, 1 gold, 1 zinc, 1 mowgles, that is 212381.06... *** Have gave: 24 anipium, 50 platinum, 1154 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 360 zinc, 1199 mowgles, that is 3134.39... ----------- give 24 anipium to bisqwit give 50 platinum to bisqwit give 1154 gold to bisqwit give 267 silver to bisqwit give 106 bronze to bisqwit give 133 copper to bisqwit give 212 tin to bisqwit give 360 zinc to bisqwit give 1199 mowgles to bisqwit emote calculates: Paid 24 anipium, 50 platinum, 1154 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 360 zinc and 1199 mowgles, totalling worth of 3134.39. ----------- ## 3.1.2. Being generous
Though... if you are really generous, you can instead pay with the
most valuable coins you have:
./batmoney -b bisqwit 3134.39causing this output: *** Now paste your inventory here (the lines saying what coins do you have): *** Thank you *** Inv at start: 402 mithril, 91 batium, 69 anipium, 53 platinum, 1155 gold, 267 silver, 106 bronze, 133 copper, 212 tin, 361 zinc, 1200 mowgles, that is 215515.45... *** first: gave 6 mithril... so I've 134.39 left to pay. *** first: gave 1 batium... so I've 34.39 left to pay. *** first: gave 3 platinum... so I've 4.39 left to pay. *** first: gave 4 gold... so I've 0.39 left to pay. *** first: gave 1 copper... so I've 0.19 left to pay. *** first: gave 1 tin... so I've 0.09 left to pay. *** first: gave 1 zinc... so I've 0.04 left to pay. *** first: gave 4 mowgles... so I've 0.00 left to pay. ----------- *** Inv now: 396 mithril, 90 batium, 69 anipium, 50 platinum, 1151 gold, 267 silver, 106 bronze, 132 copper, 211 tin, 360 zinc, 1196 mowgles, that is 212381.06... *** Have gave: 6 mithril, 1 batium, 3 platinum, 4 gold, 1 copper, 1 tin, 1 zinc, 4 mowgles, that is 3134.39... ----------- give 6 mithril to bisqwit give 1 batium to bisqwit give 3 platinum to bisqwit give 4 gold to bisqwit give 1 copper to bisqwit give 1 tin to bisqwit give 1 zinc to bisqwit give 4 mowgles to bisqwit emote calculates: Paid 6 mithril, 1 batium, 3 platinum, 4 gold, 1 copper, 1 tin, 1 zinc and 4 mowgles, totalling worth of 3134.39. ----------- ## 3.2. Being poorYou are carrying 73.1 kg of equipment: 1425 coins (1155 gold, 267 silver and 3 mowgles) [Cash: 1315 Bank: 0 Total: 1315]
## 3.2.1. Being too poor
You want to pay Bisqwit 3134.39 gold from what you're carrying. Well, you obviously don't have that much: *** Now paste your inventory here (the lines saying what coins do you have): 1425 coins (1155 gold, 267 silver and 3 mowgles) [Cash: 1315 Bank: 0 *** Thank you *** Inv at start: 1155 gold, 267 silver, 3 mowgles, that is 1315.23... *** first: gave 3 mowgles... so I've 3134.36 left to pay. *** first: gave 267 silver... so I've 2974.16 left to pay. *** first: gave 1155 gold... so I've 1819.16 left to pay. *** Inv now: that is 0.00... *** Have gave: 1155 gold, 267 silver, 3 mowgles, that is 1315.23... say [batmoney] I don't have enough money to pay with. ## 3.2.2. Having unsuitable coins
You want to drop 134.39 gold. ./batmoney 134.39Result: *** Now paste your inventory here (the lines saying what coins do you have): 1425 coins (1155 gold, 267 silver and 3 mowgles) [Cash: 1315 Bank: 0 *** Thank you *** Inv at start: 1155 gold, 267 silver, 3 mowgles, that is 1315.23... *** first: gave 3 mowgles... so I've 134.36 left to pay. *** first: gave 223 silver... so I've 0.56 left to pay. *** Inv now: 1155 gold, 44 silver, that is 1181.40... *** Have gave: 223 silver, 3 mowgles, that is 133.83... *** exchange: gave 5 silver (3.00), now I want 2.44 back... *** exchange: gave 10 gold more (10.00), now I want 12.44 back... *** exchange: didn't help... getting cash back. *** last: took 10 gold... I still need to reget 2.44. *** last: took 4 silver... I still need to reget 0.04. *** last: took 3 mowgles... I still need to reget 0.01. ----------- *** Inv now: 1155 gold, 43 silver, 3 mowgles, that is 1180.83... *** Have gave: 224 silver, that is 134.40... ----------- drop 224 silver emote calculates: Dropped 224 silver, totalling worth of 134.40. say [batmoney] I ran out of small coins, I want 0.01 back. ----------- ## 4. Algorithm used
The algorithm behind this program (the smallest coins method)
was surprisingly difficult to develope. I'll try to describe
it here.
Imagine you have "coins (1 silver, 1 tin, 12 zinc)" and you have to pay 0.8 gold. ## 4.1. Step 1: Pay with the smallest
Start with the smallest coins in the inventory.
So, we do: - pay 12 zinc, as it lessens the debt with 0.05 * 12 = 0.60, remaining = 0.20
- pay 1 tin, as it lessens the debt with 0.10 * 1 = 0.10, remaining = 0.10
## 4.2. Step 2: Initiate exchange
If you're out of coins now, there are three possibilities: - If the pay is even, you were robbed penniless.
- If you've paid too much, you don't have suitable coins and you must negotiate exchange.
- If you've paid too little, you don't have enough money.
In this example case, we pay 1 silver, as it is the smallest coin we can use to lessen the debt. This pays 0.60, making our debt now be -0.50.
## 4.3. Step 3: Peel it
After step 2, we have paid too much. You must get coins back.
This is what is the hardest part of the algorithm. If you swap
the customer and the seller now and try with Step 1, you'll end
up in an infinite loop. So my solution was to use brute force.
Test through all the possibilities of getting coins back from the
customer, starting from the biggest coins, seeing which one of the
combinations results to even pay. If none of them works, you
must jump to Step 2 and pay more coins. In this example case, the brute force reveals that getting back 1 tin (0.10) and 8 zinc (0.40) makes the pay even, and we're done. If you have any idea how to do this without brute force, I encourage you to contact me and tell me. ## 5. Copying
batmoney has been written by Joel Yliluoma, a.k.a.
Bisqwit, and is distributed under the following terms:
## 6. Requirements
GNU make is probably required.
## 7. Downloading
- Do not download everything - you only need one file (newest version for your platform)!
- Do not use download accelerators or you will be banned from this server before your download is complete!
Date (Y-md-Hi) acc Size Name 2003-0530-0300 r-- 14700 batmoney-2.01.3.tar.bz2 2003-0530-0300 r-- 2728 patch-batmoney-2.01.2-2.01.3.bz2 2002-1216-1959 r-- 14630 batmoney-2.01.2.tar.bz2 2002-1216-1959 r-- 12248 patch-batmoney-2.01.1-2.01.2.bz2 2002-1216-1957 r-- 14 patch-batmoney-2.1.1-2.1.2.bz2 2002-0501-2249 r-- 10750 batmoney-2.01.1.tar.bz2 2002-0501-2249 r-- 3449 patch-batmoney-2.01-2.01.1.bz2 2002-0209-2333 r-- 10224 batmoney-2.01.rar 2002-0209-2334 r-- 10507 batmoney-2.01.tar.bz2 2002-0209-2333 r-- 7350 patch-batmoney-2.00-2.01.bz2 2001-0202-2222 r-- 5108 batmoney-2.00.rar 2001-0202-2222 r-- 5101 batmoney-2.00.tar.bz2 2001-0202-2222 r-- 5632 batmoney-2.00.zip 2001-0202-2222 r-- 5632 patch-batmoney-1.99-2.00.bz2 2001-0202-2147 r-- 4625 batmoney-1.99.rar 2001-0202-2147 r-- 4618 batmoney-1.99.tar.bz2 2001-0202-2147 r-- 4947 batmoney-1.99.zip← Back to the source directory index at Bisqwit's homepage | ||