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LOL. It's fun stuff once in a LOOOOONG while.
Indeed, looks like it likes the support at the 31 MA
I am having DSL issues and can't mod much since I can hardly keep a connection.
SJ -- SPNG's chart should show something. It's beginning to swing properly.
Amazing. Words escape.
Will be posting results next monday, lets hope for the best! lol
HA! We filled a page.
Good luck on the exam -- keep in mind to diagonalize (as close as possible) the xyz matrix and you're golden. Also stick to the rule that the number of slacks is the number of constraints.
Also, in the last tabu, look for r=1. That gives the Max(r) and usually the other variables in that row are 0.
When I am sober... small detail there.
No prob. That's why I am here.
well thank you very much for the help tonight, and i do mean help. You didnt just shot off your math skills and give me the answer, you actually gave me step by step. Thank you very much.
Or I am insane...
Also I am working on my second PhD -- once you're in, your stuck ;oP
Nah, I love it. I'll be the eternal student and popular opinion be damned. Thinking solves problems and that's what I honestly enjoy doing.
Just went to college, worked part time, did weekend mgt of my old apartment complex, and made ends meet. It was the hardest 12 years of my life. In hindsight, I don't know how I managed, but I did.
You will too -- it's difficult but builds you into a person able to handle anything. It's kinda funny -- my everyday life seems so simple compared to the work I do.
I guess you get conditioned and develop due to the beatdown :)
where did you/do you find the time to teach yourself/be taught?
Cognac poured...better.
Oh you asked about my book collection. If you include the ones in plastic boxes, I have about 6000 books. Mostly math, physics, philosophy, art, and computer/EE.
Oh yeah... it's slow work but it is useful in the matrix formulation of mechanics/statics and quantum mechanics. Scary thing is that the energy levels of a hydrogen atom follow a similar technique. Also, stress on beams (on computer) follow this pretty much to the letter.
yes its just such a F'n hassle to do it
But do you see the method?
goddamn this sucks.
Note: 3 constraints gives 3 slacks -- no way out of it.
So the soln is:
Solution: R = 22; x = 1, y = 6, z = 0
Now the x's are done, use the rows w/ x=0 to clean up the y's:
Tableau #3
x y z s1 s2 s3 p
0 0 2 1 -1 -1 0 8
1 0 -1 0 1 -1 0 1
0 1 3 0 -1 2 0 6
0 0 3 0 1 2 1 22
This tells you:
(last row) p = 22 and z=0 (since it is in the row w/ r=1)
(second to last row) y+z=6 -> y=6.
Now you can get x by back sub, x=1. (from second row)
Note:
2z=8
y+3z=6
gives you y. (In case you're stuck.)
After clean up in the x's -- isolating x to a single row (that's the trick):
Tableau #2
x y z s1 s2 s3 p
0 1/2 7/2 1 -3/2 0 0 11
1 1/2 1/2 0 1/2 0 0 4
0 1/2 3/2 0 -1/2 1 0 3
0 -1 0 0 2 0 1 16
First step:
Tableau #1
x y z s1 s2 s3 p
3 2 5 1 0 0 0 23
2 1 1 0 1 0 0 8
1 1 2 0 0 1 0 7
-4 -3 -2 0 0 0 1 0
Ok... gonna take me a min... ugleee...
dont post until i post....
P=4x + 3y + 2z
3x + 2y + 5z <= 23
2x + y + z <= 8
x + y + 2z <=7
Simplex links added to iBOX.
Agreed. I never much cared for matrix algebra. But do you see the method?
1) Rewrite the inequalities as equalities using slacks (usually one slack per constraint equation).
2) Place in a rows/matrix form.
3) RREF the xyz (and the rest) as to get the xyz portion of the matrix as close as you can to a diagonalized matrix.
4) Write down the result algebraically from the (hopefully) diagonalized matrix and back substitute to isolate solutions.
5) Keep in mind, R=1 row is the maximized value.
my head is going to explode.
Oh gawd... brain damage from finite.
And the guiding rule is to make the xyz matrix DIAGONAL w/ as few off diagonal elements as possible. If you do that, you can isolate the variables w/ a little hassle. If you're allowed to use a HP or TI, they do RREF.
http://www-fp.mcs.anl.gov/otc/Guide/CaseStudies/simplex/feasible.html
Worth printing out someday -- good example site.
Oh, one thing of advice (forgot it until now).
The last tabu ONLY WANTS R=1 IN ONE ROW.
Else you need to keep reducing or messed up.
Damn, I haven't done that in, er, 7 years.
Tableau #3
x y z s1 s2 r
1 0 1 1/5 2/5 0 13
0 1 0 -2/5 1/5 0 2
1 0 0 0 1 1 28
Basically you're looking to make the xyz matrix diagonal like / or \ as to make finding the values for x, y, and z simpler. If possible, isolate y and z using row ops and then work backwards to x. (Usually you isolate n-1 vars and backsolve the last one.)
You know the max is 28 by the tabu.
Yes. 2 is the pivot and you use row ops to get it to 0 since you want (usually) to eliminate it.
Wait... which one in s2?
okay..so 2 is our pivot variable...do we want it to be 0 or 1? and we use row operations to get it to that??
Something like that.
wtf are you? a human library? :P
Tableau #1
x y z s1 s2 r
1 -2 1 1 0 0 9
2 1 2 0 1 0 28
-1 -1 -2 0 0 1 0
I know that we find smallest negative...but how do we get it over to slack 2 below
Tableau #2
x y z s1 s2 r
1 -2 1 1 0 0 9
0 5 0 -2 1 0 10
1 -5 0 2 0 1 18
yah i wasnt quite sure how to notate the <=
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