### LC stalls in a long process.

Posted:

**Wed Mar 18, 2015 4:57 pm**This was a challenge posted on the use-list. I bring it here to report a problem with LC and long processes. The OP wanted to find methods of determining, among a list of 26 populations, which combination would equal 100,000,000. I did it brute force, using a combinatorial handler in the MasterLibrary. But this handler never finished with 26 elements, so I kluged an even more brute-force gadget on top of that function, so that it needed only to work the first twelve, and then the remaining 14 were "added on".

Anyway, the thing works fine. In the abbreviated example here with 18 lines, to find the sum of 26978865,the answer is lines 1,9 and 18. This is still 262,000-odd combinations, and I chose it so that it finishes in just a short while. But beyond 22 lines, LC stalls and the handler quits. I wrote on the use-list:

-- Population LIST:

Craig Newman

Anyway, the thing works fine. In the abbreviated example here with 18 lines, to find the sum of 26978865,the answer is lines 1,9 and 18. This is still 262,000-odd combinations, and I chose it so that it finishes in just a short while. But beyond 22 lines, LC stalls and the handler quits. I wrote on the use-list:

Houston, we have an issue with LC.

I used the "combinatorial" function in the "MasterLibrary" for the 26 lines in the list, but the process was too slow. I made a kluge, so that a shorter call to that function was then processed by an even more brute-force routine. It works fine, but it also does not work.

LC stalls if the number of elements is greater than 22. I assume this is some sort of memory issue, unless LC just gets bored with the whole thing.

The following handlers pull an arbitrary value to test, and the gadget does indeed find the appropriate components.

Code: Select all

```
on mouseUp
--FIELD 1 HAS THE LIST OF POPULATIONS
--1,9,18 ARE AN ARBITRARY TARGET SUM
-- THIS IS A SHORTER TEST FOR 18 LINES TO PROVE CONCEPT, AND FINISH IN A SHORT TIME
get line 1 of fld 1 & "," & line 9 of fld 1 & "," & line 18 of fld 1
put sum(it) into magicNumber --29335150
put fld 1 into tList
put combinatorial(12) into accum
repeat with y = 13 to 18 --FAILS WITH A VALUE OF 26, THE ACTUAL NUMBER OF LINES IN THE LIST
put accum into tempAccum
repeat for each line tLine in tempAccum
put tLine & comma & y & return after finalAccum
end repeat
put accum & return & finalAccum into accum
put y after accum
put "" into finalAccum
end repeat
repeat for each line tLine in accum
repeat for each item tItem in tLine
put line tItem of tList & "," after temp
end repeat
if sum(temp) = magicNumber then
answer tLine
exit to top
else
put "" into temp
end if
end repeat
end mouseUp
function combinatorial n
put the cursor into tCursor
put 1 into tCursorCtr
if n >= 15 then -- make sure you know what you're in for!
answer n && "objects will result in" && (2^15 -1) && "subsets" with "Continue" or "Cancel"
if it is "Cancel" then exit to top
end if
put 1 into subsetsVar -- initialize variable
repeat until x = n -- this repeats (2^n - 2) times, which is one less than the numer of possible subsets
Add 1 to tCursorCtr
if tCursorCtr > 5000 then
set the cursor to busy
put 0 into tCursorCtr
end if
put the last line in subsetsVar into x -- each subset is used as input to compute the next subset
put the number of items in x into noItems
if item noItems of x = n then
add 1 to item (noItems -1) of x -- increment 2nd to last item if last item = n
delete the last item of x -- get rid of last item if it = n
put return & x after subsetsVar -- add another subset to list of subsets
else
put ((item noItems of x) + 1) into item (noItems + 1) of x -- increment last item
put return & x after subsetsVar -- add another subset to list of subsets
end if
end repeat
set the cursor to tCursor
return subsetsVar -- return the list of all possible subsets
end combinatorial
```

I did not try this with an array, first to see if it is faster, but also to see if it can handle the larger list. Anyone have any insight?

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Craig Newman