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Talk:Permutations with repetitions: Difference between revisions
Talk:Permutations with repetitions (view source)
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, 7 years ago→Isn't it just similar to "Increment_a_numerical_string": new section
(added a section regarding REXX limitations on the INTERPRET statement. -- ~~~~) |
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==Mathematica solution incorrect?==
The task description says combination must be produced one at a time.
The Mathematica solution uses Tuples, which return a list of all permutations at once.
Is this a correct solution?
==REXX implementation limits==
Line 5 ⟶ 11:
For Regina REXX, it depends on the release level.
For Regina REXX 3.3, 3.4, 3.5, REXX gives a SYNTAX error:
:::::: Error 12 running "C:\xxxxxx.REX", line 29: [Clause > 1024 characters]▼
For Regina REXX 3.6, 3.7, REXX "crashes" somewhere less than a statement length of 1932,▼
▲For Regina REXX 3.6, 3.7, REXX "crashes" somewhere less than a statement length of 1932,
<br>I haven't pursued this to find the exact byte count.
Line 18 ⟶ 25:
For what's it worth, I believe REXX should raise the SYNTAX condition.
[The reason I mention the older versions of Regina REXX is that Regina 3.3 REXX uses less
<br>virtual memory for those REXX programs which use a ''lot'' of stemmed variables (possibly a
<br>memory leak), so the use of the older Regina release is forced in lieu of a fix.
For PC/REXX and Personal REXX, it depends on what the RXISA ('''SET''' environmental variable).
<br>These two REXXes either give:
:::::: Error 11 on line 29 of c:\xxxxxx.REX" Control stack full
<br>
:::::: Memory full: symbol
:::::: Error 5 on line 29 of C:\xxxxxx.REX: Machine resources exhausted
somewhere between 568 and 597 bytes.
It should be noted that most people use the maximum for the RXISA (which is 40K).
As far as I can tell, R4 and ROO have no (real) limitation for the length of an INTERPRET instruction,
<br>and that is probably true of CMS REXX and TSO REXX (it's been too long since I used those
<br>two flavors of REXX).
::::::::::: -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 20:2013 (UTC)
==another variant of the REXX example==
This REXX version:
* simplifies many statements
* minimizes the length of the INTERPRET statement
* eliminates the SELECT statements
* eliminates a DO loop
* uses both kinds of quotes strings to make it easier to peruse
* moves a couple of statements out of the INTERPRET clause
* uses a positive (logic) instead of a negative IF statement
* eliminates an extra ''';''' (semicolon) from the INTERPRET clause
* eliminates the need for counting the permutations
<br>If any of these improvements could/would be of use, that's fine. I plan to delete this entry in a couple of weeks. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 04:2013 (UTC)
<lang rexx>/*REXX*/ parse arg n m s names
if n='' then n=3
if m='' then m=2
if datatype(s,'N') then s=left('',s)
do k=1 to n
if names='' then e.k=k
else parse var names e.k names
end /*k*/
a=''
do i=1 to m; a=a'do d'i"=1 to n;"; end /*i*/
a=a'z=e.d1'
do j=2 to m; a=a"||s||e.d"j; end /*j*/
a=a';say z'copies(";end",m)
if m==0 then do; say '1 permutation, a "null".'; exit; end
interpret a
say n**m 'permutations'</lang>
== Isn't it just similar to "Increment_a_numerical_string" ==
▲::::::::::: -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 20:52, 12 May 2013 (UTC)
You set the length of the string to n fill it completly with "0" and set the base to k.
▲-----
http://rosettacode.org/wiki/Increment_a_numerical_string#Pascal
Of course you can use an array of integer instead.
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