HP50G SIMPLEX Version14b Max Min Pivot Algorithm, multiple/unbounded, unfeasible sol

01262023, 03:20 PM
(This post was last modified: 01262023 03:22 PM by Gil.)
Post: #21




RE: HP4950G VERSION 12.hp SIMPLEX Max Min Pivot Algorithm, multiple/unbounded solutions
Version 12
 In some very special cases, the program could be sometimes "stuck" at the end and chose the wrong row, returning then the second solution — but possibly an unfeasible one. A special "artificial" test was duly included in subprogram CHECK. 2SOL to fix up that issue.  The NOTE Var was changed : explanations now only regarding the "pivoting" (outside the program) & no more explanations relative to roundings.  Lines of explanations in —>PIVOT¦&COL.ROW subprogram suppressed for speed purpose. 

01262023, 03:28 PM
(This post was last modified: 01292023 03:04 PM by Gil.)
Post: #22




RE: HP4950G VERSION 12.hp SIMPLEX Max Min Pivot Algorithm, multiple/unbounded solutions
New Version 12
 In some very special cases, the program could be sometimes "stuck" at the end and chose the wrong row, returning then the second solution — but possibly an unfeasible one. A special "artificial" test was duly included in subprogram CHECK.2SOL to fix up that issue.  The NOTE Var was changed : explanations now only regarding the "pivoting" (outside the program) & no more explanations relative to roundings.  Lines of explanations in —>PIVOT¦&COL.ROW subprogram suppressed for speed purpose. 

01292023, 02:54 PM
(This post was last modified: 02012023 02:10 PM by Gil.)
Post: #23




RE: HP4950G VERSION 13d.hp SIMPLEX Max Min Pivot Algorithm, multiple/unbounded solutions
Version 13d
Handling of "unfeasible" problem. For visual outlook, deletion of no more used SAME.SOL. Just look at the following problem (input Matrix) : [[ 1 1 'L' 5 ]* [ 0 1 'G' 8 ]** [ 6 4 0 'Max' ]] According to usual SIMPLEX convention (in this program), if nothing is said about xi (here x1 and x2), it is assumed to be >=0. If x2 >= 8 according to **, then * cannot be <0 as said in *, unless breaking the above rule and accepting that x1 might be <= 0 (x1=3). Put [[ 1 1 'L' 5] [ 0 1 'G' 8 ] [ 6 4 0 'Max' ]] on the stack and launch —>GO. You get then, with the new version 13d: { Var 2¦Steps 4 Time1¦s : ZMax: 14 :x1: 3 :x2: 8 : Sign { x1 } not allowed: UNFEASIBLE.problem}. Then, pressing afterwards the variable S.1N, you get also the reminder: :Unfeasible problem Sign incompatibility of { x1 }, [x1 x2... ]: [ 3 8 ] Of course, if you specify that x1 is <= 0 [[ 1 1 'L' 5 ] [ 1 0 'L' 0 ] [ 0 1 'G' 8 ] [ 6 4 0 'Max' ]] and launch —>GO with the new above Matrix, you will get: { Var 2¦Steps 5 Time1¦s : ZMax: 14 :x1: 3 :x2: 8 }, with no special message. The same applies to [[ 1 1 'L' 5 ] [ 1 0 'F' 0 ] [ 0 1 'G' 8 ] [ 6 4 0 'Max' ]], supposing x1 Free (of unknown sign). 

02012023, 02:08 PM
(This post was last modified: 02072023 09:02 AM by Gil.)
Post: #24




RE: HP50G SIMPLEX Version14 Max Min Pivot Algorithm, multiple/unbounded, unfeasible sol
Version 14
 Linear Combination of xi in prior versions supposed all xi to be >= 0 (default case), or free. Now, in the linear combination of the xi, besides the free case of xi being free, the default case respects the real signs of the xi.  Programs variables S.1N, S.LIN & d.LIN, when called, give more details about the solution (multiple/unbounded/unfeasible solution). 

02072023, 09:02 AM
Post: #25




RE: HP50G SIMPLEX Version14 Max Min Pivot Algorithm, multiple/unbounded, unfeasible sol
New Version 14b
Slight change in output for RESULT¦Ci.rows in case of unfeasible problem. 

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