Your problem is very easy to solve, it fits well a first-lesson programming
introduction course. The reason you wasted 2 days, is because you try to do it
like R, while this problem is best solved in C.
In fact, I think this problem demonstrated why R still maintain all the C
features like for/if/while -- because there are problems that should not be
solved in matrix thinking.
You want to know the "sales volme" in relation to the "minimum profit of each
hand of deals". Here is the code and here is the result in two columnes
> get_volume_by_minimum_profit_rate_per_hand_of_deal <- function(A, B, profit) {
+ i = 1
+ j = 1
+ while (A[1,i] / B[1,j] > profit + 1) {
+ # step by step find the suitable volume
+ if (sum(A[2, 1:i]) > sum(B[2, 1:j])) {
+ j = j + 1
+ } else {
+ i = i + 1
+ }
+ }
+ min(sum(A[2, 1:i]), sum(B[2, 1:j]))
+ }
>
> for (i in seq(0.01, 0.023, 0.001)) {
+ print(c(paste(i*100, "%"),
get_volume_by_minimum_profit_rate_per_hand_of_deal(to_sell_to, to_buy_from, i)))
+ }
[1] "1 %" "20580"
[1] "1.1 %" "18445"
[1] "1.2 %" "15032"
[1] "1.3 %" "11032"
[1] "1.4 %" "10766"
[1] "1.5 %" "10434"
[1] "1.6 %" "10268"
[1] "1.7 %" "10102"
[1] "1.8 %" "6867"
[1] "1.9 %" "3299"
[1] "2 %" "717"
[1] "2.1 %" "551"
[1] "2.2 %" "551"
[1] "2.3 %" "219"
See how this corrects your calculation? You calculated that "if the king
requires minimum profit of 2%, the volume (total quantity) of goods being dealt
should be a bit more than 1000", but look at your data, that means you dealet
five hands to buy, and one hand to sell -- the 5th hand you buy is at the price
of 61.9450, the one hand you sell is at the price of 63.170
(63.17/61.945 - 1) = 19.776%
so the last hand you buy doesn't quanlify minimum requirement. My calculation
is right, with the minimum requirement of 2% profit, the volume you can deal is
only 717.
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
