Simplex Explained

Here is an explanation of the simplex algorithm, including details on how to convert to standard form and a short discussion of the algorithm's time complexity.

[@osmanhajiyev]

So concise... Someone give this guy a Nobel Prize

[@LnX53]

this is legitimately gold, i've had no idea about simplex, circulated through 4 or 5 video, all of them assumed I had some knowledge prior to watching the video so I could not understand anything at all from them. But this one right here... This is perfect ! thank you

[@ibrahimrupawala3444]

I have spent hours understanding linear programming and simplex but this dude explained it better than anyone in 10 mins

[@salmaalfawal6155]

I can't believe this is the only video on your channel, it's so informative and you explained it very well!

[@voxlz]

Except for the last few seconds, which gave me horrible flashbacks, this is more or less the perfect explanation. Thanks a lot!

[@akshay-ashok]

I don't usually comment in KZbin videos. But this video right here should be appreciated. Man, you're awesome!

[@m4d_al3x]

You just summed up my 1.5hour lecture in a 10min video.

[@joebashour]

This is the most straightforward video explanation of Simplex...Very much appreciated. Thanks!

[@AbdallahBoukouffallah]

Old yet still the best

[@pengliu6245]

The only excellent video explains the simplex algorithm very clearly! Many thanks.

[@ilikechocolate3741]

at 8:07 the column S2, third row, the number should be 10/3, not 15/4. Also, you didn't mention artificial variables, two phase simplex and duality at all. With that being said, very good video, I'd give you a 9/10

[@janplechaty1702]

Yes, I got that too. I think there was a mistake with -1/3 on the S2 above that 15/4, because S2 on the second row should be just 1/3, not -1/3. Thank you for your comment and thanks to author for his explanation.

[@CauseOfBSOD]

@@janplechaty1702 indeed, I have been implementing the algorithm for a computer science project. Test case (problem from this video) kept failing because of this. Eventually worked through the algorithm by hand and got the same result my implementation gave (i.e. both S2 row 3 being 10/3 and S2 row 2 being 1/3 are the correct answers)

[@daesoolee1083]

Read and watched several explanations about the Simplex but this video is the best. It starts with the overall idea and gets deeper and deeper, which helps the understanding quite a lot.

[@gabrieltepin]

This must be one of the best content in the whole youtube, amazing

[@krischalkhanal234]

So concise yet so perfect. And so intuitive and elementary too.

[@titanictypist9062]

Holy cow dude! This was VERY well explained. Inspiring.

[@chicagogirl9862]

I searched a lot and I've been confused totally but you explained very good:)

[@oliviergagnon5918]

Best demonstration around. And would be hard to beat. Thanks.

[@warsicklol]

Simple and clear explanation. Thank you for making this video

[@Helen-lm6bb]

I don't know why your channel isn't popular! Great explanation for people who don't have prior knowledge to such algorithm. Thanks!

[@aziz99]

man you re a life saver , also that scene from dhis is pure gold, bless you

[@debonairrose]

his voice fits being the main vocal of a rock band i swear to god.

[@ayushbhatnagar8091]

At 9:15, Case where x is negative, I think you need to add one more constraint x_1< x_2 and need to include them in the objective function as well. Great explanation btw.

[@reshmithampy]

Now I have an idea about what I am to do and not feel forced to memorize the steps

[@luigiduprez7510]

I would love to see more videos from him, a very nice way of explaining and visualising the concept

[@erazn9077]

At 8:08 shouldn’t the 4th value for the last row be 10/3 instead of 15/4? 5 + ( - 5 / 3 )

[@santoshkavhar2596]

Thanks so much for simplifying it so much, textbooks make it way more harder. I hope you keep making more videos

[@wexwexexort]

Really nice explanation, clear and to the point.

[@VietnamSteven]

your presentation style is really outstanding!!

[@earthling123]

"A quick sanity check" always gets me 😂

[@razamailbox]

Great Explanation, finally a video which gives some intuition Thank you!!

[@elliott8175]

So, this vid is amazingly concise; but I got me some questions: 1) How do you choose the first vertex? In this case it's "obvious" that (0,0) is a vertex, but I have a problem with over 100k decision variables and if I set them all to zero then I'll be outside the solution region. 2) How to handle constraints that don't form a boundary? Imagine the same as above, but with the added constraint *x

[@julianocamargo6674]

1 - This is the purpose of the slack variables. If the right side vector b is positive, you can always start with x=0 ans s=b. Some problems do not have postive b, and then indeed it is another problem. It is called the 'first phase' of simplex algorithm. You have to start with what we call a "basic feasible solution"

[@julianocamargo6674]

2 It seems the process of changing the base was not explained, but in simplex if you start with a bfs vertex, you always get another bfs (improved) vertex. When you change the point you test how far can you move it in a given direction, and then your redundant constraint would never show up. Since some constraints add nothing to the problem, some solvers can do a preprocessing and remove it just to make the matrix smaller .

[@elliott8175]

@@julianocamargo6674 Thanks for your explanations! I wish I could give an intelligent response, but I haven't touched simplex since I first wrote this comment. I'm sure I'll come back to it and read your comments again. Thanks. =)

[@faresmajed50]

I wish you are my instructor, thank you so much for this short and concise video

[@4BohrKid]

best explanation i've seen so far.

[@TheMyanka]

Thank you, that was a brilliant explanation.

[@1tokillamockingbird]

LEGEND! You can die in peace knowing that your legacy will forever save future undergrad students days before their final exam

[@shershahdrimighdelih]

Very well presented, and the jump cuts help understand things better

[@lstathisplaysvideogames4906]

My guy, you just saved my ass , my professor could never

[@abdulrehmanbilal958]

OMG This opened the doors of my thoughts.

[@mouhamethfadalmarabyaidara4935]

concise and accurate explanation.Great video and thanks a lot

[@markkaravan4245]

Amazing explanation. Not nearly enough subscribers.

[@theatulupadhyay]

Very beautifully explained.

[@valentinegift3689]

Dude you are wonderful - really wish you'll somehow monetize your explanation skills.

[@MuhsinFatih]

I am experiencing mathgasm. So elaborately put. Awesome video

[@atakan716]

awesome explanation 🎉

[@ZenoDiac]

Beautifully explained

[@whasuklee]

Such a great help! Really appreciate your work!!

[@ruslanaliev2216]

best explanation of simplex ever!

[@danielTkachenko0]

That's a great explanation! Thanks for the video

[@pacmanmaster16]

Great video, you should make a comeback

[@toxictime3862]

This is awesome! Please do more

[@ankitunariya3661]

YOU R A GENIUS ! THANKS A LOT.

[@sjwang3892]

Thanks for this great video!

[@n-da-bunka2650]

Perhaps it was my linear computation classes from 1981 kicking in but didn't everyone know the answer the minute it was asked? I started to wonder why he was presenting such an obvious solution and kept waiting for the trick that I may have originally missed which, of course, doesn't exists.

[@Traymer7]

Perfect man! Love that you implemented theory as well!

[@bakdorz]

Great explanation! Question though: Once we reach intersection at B ( 4:35 ) you mention that we have TWO options. Keep b=0, or keep s2=0. I'm not sure I understand how come we have two options, since if we chose b-0, then the objective would decrease no?

[@elliott8175]

Yeah, I think you're always strictly improving on the solution, so surely you could always rule-out the vertex that you just came from. For 2D problems that'd mean doing a circuit till you're at the max.

[@estelle367]

🤓

[@gat0tsu]

very clear. amazing. wow

[@mathaha2922]

Excellent!

[@vaggelismanousakis6147]

Simplex explained Simply. Thaks a lot

[@waheebalqamar558]

Man, you are the best

[@saranshgokhale8298]

Very helpful, thank you!

[@jared0801]

thanks for the straightforward explanation

[@ansyona7522]

Thank you for sparing many hours of torture for many!!

[@Physicus9]

Am I the only one wondering how at 8:05 he managed to get 15/4 for the 5-(5*(-1/3))? That would be 10/3 if I'm not mistaken...

[@louisholley7944]

Michael Duffy you are correct, but fortunately here that doesn’t matter. Thanks for pointing out the mistake :)

[@user-wq5lv8nx9s]

Mistake at 8:04 second row -1/3 on the right should be 1/3 and the 15/4 should be 10/3 everything else is all good.

[@prasadkavinda1210]

thanks man. very helpful!!

[@ericc6820]

well said 👏

[@tapobrataroychoudhury3016]

Thank you❤

[@nischalsubedi9432]

@ 2.25 timestamp--did you mean s1

[@elliott8175]

*S* represents the amount that you would need to add to the smaller amount (lhs) to make it equal to the larger amount (rhs). So *S1* and *S2* should be strictly non-negative.

[@crystalline2]

that was interesting, very good explanation thank you

[@earthling123]

Thank you louis

[@austinoquinn815]

Wow, that was great.

[@iambossgetlost1395]

👌

[@InvincibleAirman]

I came here to understand the reasons behind the matrix manipulation better, but when the video reached that part, it kind of stopped explaining (why things are done) and settled for narrating (what is being done, which I already know) so I didn't find it as helpful as I had hoped.

[@lopyus]

Thank you so much! =)

[@ElectromecanicaIndustrial]

thank you

[@Alex-op2kc]

good video

[@nipo4144]

why do we want the smallest ratio at 6:58?

[@24mrdanny]

I am wondering this as well...

[@nipo4144]

@@24mrdanny this smallest ratio allows us to keep the constraints on variables. on a graph it corresponds to moving along the edge until u encounter the first constraint.

[@javad346]

Thanks a lot

[@thangible]

i love this.

[@BipinOli90]

good explanation

[@shaky3]

thank you! you made simplex simple lol

[@DlcEnergy]

you mean, Complex Explained

[@pathfinder750]

what a legend

[@XShollaj]

Perfection

[@tayyabm_edits]

welcome to 2021.

[@arielediang5381]

s1 and s2 aren't supposed to be great or equal to zero? why do you s1 and s1 are less than zero while drawing the graph?

[@kushb5419]

thank you!

[@heoTheo]

awesome!

[@antoinecolson9989]

you did not explain why at 6:40 you take the constants in the last column and divide them by their corresponding values in the first column. This video does not explain the simplex method, it simply describes it.

[@abikim3438]

from the drawing, how can i know if there is unused material or hours ?

[@nandaschuch]

You are producing 20 of each chair, which use 3m2, so in total you use 120m2 (40*3m2) which is the maximum allowed by the problem, so no unused material. The same for the hours, the full 1000 hours were used (20*40+20*10).

[@ramananm6257]

The irony is Simple is not actually "Simple"!! (The big table thing, Oh God 🤯)

[@authenticstories2571]

great

[@kevinchou4147]

vivid example

[@almakyubi]

tysm

[@steven1671]

That intro sound sounds familiar.... dont hug me I'm scared.

[@louisholley7944]

Steven :)

[@pakonicoco]

Might be either dumb or too late.. but why not only sell standard chairs? As I am understanding it, you are essentially loosing profit with every “luxury” chair you sell.. if you spent the 1000 hours on 100 “standard” chairs (costing 10 hours each) you would make $1000 at $10 each. If you made a single “luxury” one and the rest “standard”, you would make $980. If you made two “luxury” chairs and the rest “standard”, you would make $960.. i.e. you are loosing $20 for every chair. It costs you twice in labor to profit for every luxury chair, compared to a one to one cost in labor to profit for standard chairs. What the hell am I missing?

[@nils3989]

you can only make a maximumof 40 chairs due to the m3 of wood available.

[@pakonicoco]

@@nils3989 Ohhhh thats the detail I overlooked. Thank you for pointing it out.

[@clutterArranger]

I am a computery guy.

[@ilyasaroui7745]

don't click 7:01

[@ПавлоЛінн]

all the trickery with divisions still not explained.

[@estelle367]

i likz your accent