not sure if you guys gives a shit but if you're bored like me atm you can stream all the latest movies and series on Instaflixxer. Have been binge watching with my gf recently xD
Dude you are the best. My professor explained it in lecture and it flew over my head. The way you did it is so easy. Now looking back I understand what my prof. said. Thanks!
I am gonna cry!!Searching for a proper explanation for almost a whole day and finally!!Well explanation!!Finally understood!!You are my life saver!!Thank you!!
So nicely explained. Indian instructors are making so difficult to understand all over youtube for such a simple problem. Thank you Brian making such a useful and easy to understand video.
5 років тому+5
Hands on, the most clear and to the point explanation! Thank you for not wasting people's time! :)
My online prof taught this with what sounds like a mid 90's Burger King Drive through microphone on a windy day, and the audio only played in one ear, appreciate this bro
Thank you so much! I've been struggling with this since several hours but with your explanation I understood it in a couple of minutes. Thanks so much!
Great video! It was really helpful. I was struggling with the Simplex Method, and my professor didn't explain it so well. But this video made it so clear! Thanks!
Usually. Standard minimization problems are transformed to a standard maximization by using something called a Primal/Dual Table. I don't have a video on that, but if you search youtube for 'simplex method standard minimization,' the first video by Scott Elliot looks promising. He also has a non-standard minimization video.
i just want to know why the Z column is called the junk column ? besides your explanation was by far clearer although i did not understand how you could tell if the columns were basic.
Basic columns are 'unit' columns. Unit columns are columns that can be written with a 1 and the rest 0s. So (1,0,0) or (0, 1, 0 , 0) or (0, 0, 1, 0, 0).
Even though we are trying to row reduce, the element we pivot around in the Simplex Method matters. Because 90 is the smallest ratio, we need to pivot around that row. That's why we pivot around the '2'. You can still switch rows. It just won't change the element you pivot around.
The solution is x = 48, y = 84, and z = 0. If you let z = 60, it won't satisfy the initial inequalities. When you're done with the simplex algorithm, you read off the table like w was a basic variable. w = 60 doesn't really mean anything directly. z = 0 means the z-variable wasn't actually needed to give an optimal solution. If you think of how solutions are interpreted geometrically, the corner where the system is optimized occurred on the z-plane (z = 0). So z is like a junk variable now.
Basic columns are just columns with a '1' and the rest '0's. It just turns out that the 'w' column ends up being a basic column. Back when we introduced the slack variables, it just means 'w' was needed in order to get the equal sign.
Philippe De Soure Think of it like row reducing a matrix. You want to get your columns so that they have a 1 and the rest 0s. For the simplex method, they just call this a Basic Column. Non-Basic columns (or commonly called junk columns) don't have this form and tell you that the variable was not needed (i.e, z = 0). Honestly, I haven't looked into the how and why this method works.
hi brian thank u so much first of all even though only in the middle of the video but seems a lot clearer can you just explain why u have multiplied the first row by 0.5? why did you choose a half?
+Simon Bentley The first element in the first row is my pivot element. The most straightforward way of starting the row operation process is to make the pivot element into a "1". Since the number is a "2", I multiplied the row by 1/2. This turns the 2 into a "1". You can also divide the row by 2 (but that's basically doing the same thing).
Thanks a lot Brian!!Very much informative...I wanted to know whether any video for minimization problem too.. do we need to convert a minimization problem to a max problem to solve it?
My explanation may not be amazing but I'll give it a try. Remember when you solved systems of equations? Like 2x+y=10 and x-y=4? The answer was the intersection of the two lines. With systems of linear inequalities the answer is not an intersection but an entire shaded region. But when adding the objective function, i.e., Maximize P=2x+4y, the answer must now be at a corner (i.e, intersection of two lines) of the shaded region. We can't use augmented matrices until we have equal signs. We introduce the slack variables so that both sides now balance to give us an equals. For example, 2+5
Brian Veitch I understand the concept of slack variables. I'm not sure I completely understand what you're writing since English isn't my native language but I wondered if these variables have a meaning like the explanation of "λ" in langrange optimization. thanks for the answer anyway.
Honestly they just represent the resources in the LP problem that are not used. I'm sure there is a much more technical answer but none that have helped me understand them more. The theory can get really abstract when you venture into the high level graduate courses. But for lower level undergraduate math classes (where this is usually introduced) they are used so we can use an augmented matrix and to keep track of how much of a variable we do or do not need. I'm sorry I couldn't help more.
You can't use this technique right away. For a standard minimization problem you need to set up a dual table. This eventually leads you to a new system of inequalities. Then you can use this technique. Reading the final answer from the table is also different. I have a flow chart in the video description to help guide you through the process. I recommend ua-cam.com/video/BdtdYlUIXak/v-deo.html. This video lays out the process pretty well.
It means the equation associated with that inequality was not satisfied. It makes more sense when it comes from a word problem. Say for example you want to sell three types of chairs. Chair A takes 1.25 hour, B takes 2 hours, and C takes 3 hours. With an 8 hour workday, this gives us the total hours spent in one day as 1.25x + 2y + 3z
So I assume if looking for min, then you would be looking for, in the first Simplex Table, the largest one (while you looked for the most negaive, i.e. the smallest)??
In the first table, you divided each constant by the pivot element, so, in the third row you divided the constant (240) by the pivot element (2) to get 120. This is all fine, but while transferring the constants to the second table you used 240 instead of 120 as the constant for the last row. I believe this is a mistake.
Hi, at 4:30 you used row operations to turn the numbers of the last 3 rows in the first column into zeroes. Why'd you do that? And what if my pivot is in the middle, e.g.: column 2, row 2.
+lynx821 It's like row reducing with matrices. Whatever is your pivot element, you turn it into a 1 and the rest of the numbers in that column to 0s. In your example if we pivot around column 2, row 2 then you turn the 3 into a 1 and the 1/2, 1, and -5 into 0s.
how did you determine which variables are basic and which are not? And, you never seem to bother with entering variable or leaving variable, therefore, how did you properly interpret the final table??
What Happens if the second pivot element is in the same row as the first pivot element? This would mean that the 1 in the first column would change as the second pivot element becomes a 1.
I have an idea but I need to get my hands on that calculator. There are a lot of different versions of a casio fx scientific calculator. I teach a lecture of 120 students today and maybe one of them has one for me to look at.
Hi, i've got a question for 1st pivoting step. What's going un with all row if x in 2nd or 3rd equation is equal 0? We are leaving all row without any changes ? Thank You for an anwser.
@Brian Veitch I understand that basic columns are those, where in objective function row is 0 (so x, y and w maches that rule) but what about P? It has 1 in objective function row. Is P an exception from that rule? Maybe there is another rule for that? Or is it always considered as a basic column? Thanks in advance for Your help.
Bartosz A. It’s not that there’s a 0 in the objective function row. It’s that the column is a unit column (a column with a single 1 and the rest 0s). So the P column satisfies that rule.
+Brian Hi Brian I did a question and got this matrix..... 1 1.2 0.2 0 0 2 0 4.4 -0.6 1 0 10 0 6.8 1.8 0 1 18 How do I know what my shadow prices and reduced costs are? What's the rule for each problem I come across?
Check out my new Simplex Method app for iPhone and iPads. The link is in the description.
not sure if you guys gives a shit but if you're bored like me atm you can stream all the latest movies and series on Instaflixxer. Have been binge watching with my gf recently xD
@Korbyn Xander yea, I've been using InstaFlixxer for since november myself :)
8 years after publishing, still helping out people. Thank you Brian.
3 years after publishing, still helping out people. Thank you Brian.
Dude you are the best. My professor explained it in lecture and it flew over my head. The way you did it is so easy. Now looking back I understand what my prof. said. Thanks!
I agree. My professor knows this, but I just didn't get it. This video explains it so well that I even think it's easy.
Thanks for teaching me in 10min what my professor tried to teach for 10 hours
I am gonna cry!!Searching for a proper explanation for almost a whole day and finally!!Well explanation!!Finally understood!!You are my life saver!!Thank you!!
So nicely explained. Indian instructors are making so difficult to understand all over youtube for such a simple problem. Thank you Brian making such a useful and easy to understand video.
Hands on, the most clear and to the point explanation! Thank you for not wasting people's time! :)
My online prof taught this with what sounds like a mid 90's Burger King Drive through microphone on a windy day, and the audio only played in one ear, appreciate this bro
I finally leanred simplex only by a simple 12 min video!!! I HAVE STRUGGLED WITH THIS METHOD 3 SEMESTERS NOW!!!!!
Thank you so much! I've been struggling with this since several hours but with your explanation I understood it in a couple of minutes. Thanks so much!
+Brian Vietch This is fantastic. I watched other people do this and your version is by far the most clear. Thank you thank you.
+Grant Smith Thanks for the compliment
ONLY video that made me understand simplex method. I tried like 10 videos before.
Thank You. I would love to have teachers like you on school.
A very good explanation of the Simplex Method that i didn't find in any of the books or other references...great job sir..
Great video! It was really helpful. I was struggling with the Simplex Method, and my professor didn't explain it so well. But this video made it so clear! Thanks!
Need a 7.2 on today's test, you probably helped me out for like 2+ points, thanks mate!
Clear & concise. THE BEST tutorial I've seen on Simplex Method. Thank you, you helped a student big time.
well, i have my final exam in 12 hours, and this will be on it, but i think you have just saved my ass
Usually. Standard minimization problems are transformed to a standard maximization by using something called a Primal/Dual Table. I don't have a video on that, but if you search youtube for 'simplex method standard minimization,' the first video by Scott Elliot looks promising. He also has a non-standard minimization video.
thank you saved my final
Thank you for showing us how to use this complicated calculator. ❤
Thanks a bunch sir , i've literally tried every other tutorials out there ,this was the first one to get me my answer , thanks a lot , i'll sub you !
this is the exact same problem given to me in our homework. thank you so much!!
i just want to know why the Z column is called the junk column ? besides your explanation was by far clearer although i did not understand how you could tell if the columns were basic.
Im really worried about this method. But this video helps me to understand easily. Thank U a LOT
Excellent explanation. The best I have seen, Bravo.
bro this my first comment on youtube and I must say that it helped a lot thanks bro !
Basic columns are 'unit' columns. Unit columns are columns that can be written with a 1 and the rest 0s. So (1,0,0) or (0, 1, 0 , 0) or (0, 0, 1, 0, 0).
Awesome review! Made it so much simpler and very clear! Thank you for sharing your knowledge. - Engineering Student
Thank you so much for your step-by-step video. Soooo easy to follow...
Even though we are trying to row reduce, the element we pivot around in the Simplex Method matters. Because 90 is the smallest ratio, we need to pivot around that row. That's why we pivot around the '2'. You can still switch rows. It just won't change the element you pivot around.
The solution is x = 48, y = 84, and z = 0. If you let z = 60, it won't satisfy the initial inequalities. When you're done with the simplex algorithm, you read off the table like w was a basic variable. w = 60 doesn't really mean anything directly. z = 0 means the z-variable wasn't actually needed to give an optimal solution. If you think of how solutions are interpreted geometrically, the corner where the system is optimized occurred on the z-plane (z = 0). So z is like a junk variable now.
Thank you so much!!its the only video that helped me solve the second table!!!!!
Great explanation, probably one of the best vids explaining it. But I think I'll just stick to coordinate graphing.... lol
best explantation ever! Thank you so much
Basic columns are just columns with a '1' and the rest '0's. It just turns out that the 'w' column ends up being a basic column. Back when we introduced the slack variables, it just means 'w' was needed in order to get the equal sign.
Thanks you saved my ass on my upcoming math final
I didn't quite understand why the concept of the Basic and Non-basic columns. Why is Z for example an Non-Basic column? Great Video!
Kind Regards
Philippe De Soure Think of it like row reducing a matrix. You want to get your columns so that they have a 1 and the rest 0s. For the simplex method, they just call this a Basic Column. Non-Basic columns (or commonly called junk columns) don't have this form and tell you that the variable was not needed (i.e, z = 0). Honestly, I haven't looked into the how and why this method works.
You are my man. This was just the right video for my project
Best explanation for me so far, thanks
it's best I have seen about simplex lecture! great
bro you are awsum . been trying to figure it out from the books and they used so much of ki fi and pi terms to confuse the hell out of me ....
hi brian thank u so much first of all even though only in the middle of the video but seems a lot clearer can you just explain why u have multiplied the first row by 0.5? why did you choose a half?
+Simon Bentley The first element in the first row is my pivot element. The most straightforward way of starting the row operation process is to make the pivot element into a "1". Since the number is a "2", I multiplied the row by 1/2. This turns the 2 into a "1". You can also divide the row by 2 (but that's basically doing the same thing).
Thanks a lot Brian!!Very much informative...I wanted to know whether any video for minimization problem too.. do we need to convert a minimization problem to a max problem to solve it?
Work of Art! Great solution.
Thank you.
Geezzz thank you so much bro! You really save me from my reporting about simplex method in lpp thank you so much!..
you teach better than my Econ lecture
oh my gosh thank you! the video was insanely helpful
I have a question. Do slack variables have a meaning? Except helping us solve it of course.
Amazing explanation by the way.
My explanation may not be amazing but I'll give it a try. Remember when you solved systems of equations? Like 2x+y=10 and x-y=4? The answer was the intersection of the two lines.
With systems of linear inequalities the answer is not an intersection but an entire shaded region. But when adding the objective function, i.e., Maximize P=2x+4y, the answer must now be at a corner (i.e, intersection of two lines) of the shaded region.
We can't use augmented matrices until we have equal signs. We introduce the slack variables so that both sides now balance to give us an equals. For example, 2+5
Brian Veitch I understand the concept of slack variables. I'm not sure I completely understand what you're writing since English isn't my native language but I wondered if these variables have a meaning like the explanation of "λ" in langrange optimization.
thanks for the answer anyway.
Honestly they just represent the resources in the LP problem that are not used. I'm sure there is a much more technical answer but none that have helped me understand them more. The theory can get really abstract when you venture into the high level graduate courses. But for lower level undergraduate math classes (where this is usually introduced) they are used so we can use an augmented matrix and to keep track of how much of a variable we do or do not need.
I'm sorry I couldn't help more.
Thank you: very well done. Great effort and nice pedagogical style.
great video. Can i know what app u use for explaining this? Would love to know it.
I'm using camtasia for filming and smoothdraw to draw.
Thanks Brian.. I did watch the one by Scott and solved it.
Very helpful, thanks.
Just cracked the code thanks to this video. Been looking for someone to explain it right for hours. Thank you!!
Hello thank you for clear explanation can I use this method for minimization problem ?
You can't use this technique right away. For a standard minimization problem you need to set up a dual table. This eventually leads you to a new system of inequalities. Then you can use this technique. Reading the final answer from the table is also different. I have a flow chart in the video description to help guide you through the process. I recommend ua-cam.com/video/BdtdYlUIXak/v-deo.html. This video lays out the process pretty well.
@@BrianVeitch Thank you very much 🤗🌹
To find the maximum, don't you pick the largest value from the objective function and the largest from the divided rows too?
Thank you very much you're a legend mate!!
P=0.16x+ 0.14y
x+y
What does it mean to have 60 of slack variable of W ?
It means the equation associated with that inequality was not satisfied. It makes more sense when it comes from a word problem. Say for example you want to sell three types of chairs. Chair A takes 1.25 hour, B takes 2 hours, and C takes 3 hours. With an 8 hour workday, this gives us the total hours spent in one day as
1.25x + 2y + 3z
@@BrianVeitch thank you so much !
So I assume if looking for min, then you would be looking for, in the first Simplex Table, the largest one (while you looked for the most negaive, i.e. the smallest)??
+DarthAlphaTheGreat largest "negative" is the smallest number ultimately.
thanks a lot!! you have a very nice way of explaining the concept :)
Thanks for this, now i alreday understand what is max.
where do you get that awesome calculator, Sir?
Thank you so much for the video!
sorry how to decide which is column is basic or nonbasic? and thank you so much!
if a column has all zeros except 1 one, that would be basic
Amazing video, it's really good.
Thank you very much. it was very helpful to me :)
ahhh i looked down and found the answer already :D Thanks muchly for this incredible video
Very helpful, thank you so much!
Thanks for wonderful explanation but why z is not basic column but w is basic?
w is basic because the w column is a unit column (one 1 and the rest 0s).
Brian Veitch thanx
In a second table, third row , ratio should be 120. By Dr.Mrs.S.Kanchana
Why? I'm not dividing the third row by 2. When I do the row operation R3-2*R1 I get 240 - 2*90 = 60.
but you divided the first and second row by 2!
In the first table, you divided each constant by the pivot element, so, in the third row you divided the constant (240) by the pivot element (2) to get 120. This is all fine, but while transferring the constants to the second table you used 240 instead of 120 as the constant for the last row. I believe this is a mistake.
Okay i know understand. The division was only to determine pivot row. Its clear now.
Hi, at 4:30 you used row operations to turn the numbers of the last 3 rows in the first column into zeroes. Why'd you do that? And what if my pivot is in the middle, e.g.: column 2, row 2.
+lynx821 It's like row reducing with matrices. Whatever is your pivot element, you turn it into a 1 and the rest of the numbers in that column to 0s. In your example if we pivot around column 2, row 2 then you turn the 3 into a 1 and the 1/2, 1, and -5 into 0s.
+Brian Veitch All right, thanks a lot man! Saved me a lot of time and my mid years.
❤️... I love the application
Thanks a lot, Brian! :)
how did you determine which variables are basic and which are not? And, you never seem to bother with entering variable or leaving variable, therefore, how did you properly interpret the final table??
thanks a lot, what software do you use? the board and calculator?
thanks that was very helpful
very helpful... thanks!!!
thank you easy way
Thank you so much
Thanks great video
Hey, what if you do the ratio test and you have a negative number, what do you do then?
What Happens if the second pivot element is in the same row as the first pivot element? This would mean that the 1 in the first column would change as the second pivot element becomes a 1.
Avinand Rampersaud That's a good question. I don't know the answer to that. I suppose if it happens then you just keep working the table as usual.
Nice job keep it up
How can you decide which one is basic column and which one is junk?
very helpful thanks
hello there, how did you re write the objective function? how did it all turn to negatives?
Please help me. Thank you
5:51
Guys, which mode on the calculator CASIO must I choose in order to perform such calculations?
even i want to know..please tell
I'm not sure what you mean by mode. Are you talking about how I do the row operations in my calculator?
i m using casio fx-991ES PLUS ..so how to do row operation in that model?
I have an idea but I need to get my hands on that calculator. There are a lot of different versions of a casio fx scientific calculator. I teach a lecture of 120 students today and maybe one of them has one for me to look at.
please check..that would be a great help to me..thabkyou
Hi, i've got a question for 1st pivoting step. What's going un with all row if x in 2nd or 3rd equation is equal 0? We are leaving all row without any changes ? Thank You for an anwser.
+Majkel matka teresa I'm not sure what you mean.
dude thanks a lot!
very helpfull !!!
Keep up the Good Work....
btw. what does it mean when W=60?
thanks,,,, I have solved my homework recently :D
@Brian Veitch I understand that basic columns are those, where in objective function row is 0 (so x, y and w maches that rule) but what about P? It has 1 in objective function row. Is P an exception from that rule? Maybe there is another rule for that? Or is it always considered as a basic column?
Thanks in advance for Your help.
Bartosz A. It’s not that there’s a 0 in the objective function row. It’s that the column is a unit column (a column with a single 1 and the rest 0s). So the P column satisfies that rule.
@@BrianVeitch Ah, i see now. Thank You!
thank u sir for the tutorial, very clear. ;)
what happens if we get same values wen dividing C column with pivot column..
like your initial C column was 600 ,300, 1000?
please reply fast..
If you get the same ratio then you should be able to choose either one.
+Brian Veitch ,thnx ..this is a really gud method..
+Brian
Hi Brian I did a question and got this matrix.....
1 1.2 0.2 0 0 2
0 4.4 -0.6 1 0 10
0 6.8 1.8 0 1 18
How do I know what my shadow prices and reduced costs are? What's the rule for each problem I come across?
What was the original problem?
At 8.05, shouldn't it be 120 rather than 240?
I don’t understand where the 0’s come from why it’s 0 0 then a random 1??? In the simplex table?