Integral Battle! With Floor Functions

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blackpenredpen

blackpenredpen

5 жыл бұрын

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Integral battle between integral of (floor(x))^2 vs. integral of floor(x^2)
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Пікірлер: 104
@SHASHANKRUSTAGII
@SHASHANKRUSTAGII 5 жыл бұрын
Only a teacher who loves his subject can make more teachers. You are awesome sir. Love you from India
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Thanks!
@Daniel-ef6gg
@Daniel-ef6gg 5 жыл бұрын
For the second integral, instead of using those really long and skinny rectangles with widths along the x-axis, it would be easier to take the 60 as equal to the full x domain (4) times the full y range (15), then subtract out rectangles with widths along the y axis. There are 15 of them, they each have width 1, and they each have length sqrt(n), for n from 1 to 15.
@benjamingiribonimonteiro9393
@benjamingiribonimonteiro9393 5 жыл бұрын
Congratulations for 200k subscribers! Awesome content as always, love your channel
@jzanimates2352
@jzanimates2352 5 жыл бұрын
Blackpenredpen you have 200K subs! Congrats!
@SteamPunkLV
@SteamPunkLV 5 жыл бұрын
you can hear people cheering at 1:50
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Thanks!!!!!
@timka3244
@timka3244 5 жыл бұрын
But it is deserve 50 million subs
@0_-
@0_- 3 жыл бұрын
Now he has 750K
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
1. Consider the integral from a to b of f[floor(x)]. You can use the connection rule of integration to separate this integral into three integrals, from the intervals a to floor(a), floor(a) to floor(b), and floor(b) to b. Do make sure that a < b for simplicity, which can always be ensured, because if you have an integral from b to a when b > a, then you can switch the order of integration by multiplying by -1. Then evaluate each separately, which merely involves taking the area of rectangles. In particular, the integral from floor(a) to floor(b) is equal to the sum of f(n) from n = floor(a) to n = floor(b) - 1. The integral from a to floor(a) is simply f[floor(a)]·[floor(a) - a]. Depending on your definition of {x}, the latter could simply be -f[floor(a)]·{a}. Meanwhile, the integral from floor b to b is simply f[floor(b)]·[b - floor(b)] = f[floor(b)]·{b}. Combining all three gives that the integral from a to b of f[floor(x)] is (f[floor(b)]·{b} - f[floor(a)]·{a}) + S[floor(a), floor(b) - 1; f(n)], where S[floor(a), floor(b) - 1; f(n)] is the sum from n = floor(a) to floor(b) - 1 of f(n). This works for any f and any interval of the real numbers.
@i_am_anxious0247
@i_am_anxious0247 5 жыл бұрын
Yo! Congrats on 200k subs 1/(1-x), you deserve it man! Actually, no. You deserve way more than that.
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Pi is the best Thank you!!!!
@i_am_anxious0247
@i_am_anxious0247 5 жыл бұрын
blackpenredpen you’re awesome man, love your vids! Keep up the great work!
@ayanacharya9747
@ayanacharya9747 5 жыл бұрын
Awesomely done!!!
@ghislaindebusbecq8864
@ghislaindebusbecq8864 3 жыл бұрын
That's a 600k+ subscribers ! Congratulations. I would have drawn the parabola y=x^2 for the second integral.
@shandyverdyo7688
@shandyverdyo7688 5 жыл бұрын
I check on geogebra for this integral and it's match with ur answer. Just YAY! First integral is 14 and the second is 19,52
@soumyachandrakar9100
@soumyachandrakar9100 5 жыл бұрын
Congratulations! on 200k subscribers!!!!! yay...yay...yay
@dr.rahulgupta7573
@dr.rahulgupta7573 3 жыл бұрын
Excellent presentation of the topics in a simple manner. Thanks with sincere regards DrRahul Rohtak Haryana India
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
200K subs! Looks like you will make it to 400K before the end of the year Also, the link on the description only gives the sum of the first n squares, not the first n square roots, or so it appears. You could define a recursive formula, though, I think
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Thanks Angel!! I think I can hit 300k without problem but 400k is a bit challenging.
@kimothefungenuis
@kimothefungenuis 5 жыл бұрын
I think a good advice if you want to expand beyond 400k subs is by going on multiple social media websites . Don't stop at youtube. Go to Facebook, twitter , tumblr etc. . And also a good idea is to translate your video into more languages so your content can be seen by people from multiple countries . However, my advice is theoritical,not sure how it's going to work practically
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Hi Kimo, thanks for the comment. I am already on twitter but not fb. The translation idea will work however it will take a tremendous amount of time (or money) of me to do so. I might be able to do some for some of my popular videos but certainly not all. Thanks again for your input.
@kimothefungenuis
@kimothefungenuis 5 жыл бұрын
Your welcome and my actual name is karim
@blackpenredpen
@blackpenredpen 5 жыл бұрын
kimo the fun genius thanks karim
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
2. Consider the integral of floor[f(x)] from a to b, with respect to x. If f is piecewise continuous in the interval, then there exists some set {c_1, c_2, ..., c_k} contained in the interval (a, b), possibly the empty set, such that for all ε > 0, f(c_i - ε) < n_i & f(c_i + ε) > n_i, where n_i indexes over a set of integers in the range of f. If this set is non empty, then you can consider the integrals from a to c_1 of floor[f(x)] + integral from c_1 to c_2 floor[f(x)] + ••• + integral c_(k - 1) to c_k floor[f(x)] + integral c_k to b floor[f(x)]. Now each integró is trivially given, since floor[f(x)] is a constant in each interval, though a different one in each interval. An integral from c_i to c_(i + 1) of floor[f(x)] is equal to (n_i)[c_(i + 1) - c_i], where n_i is the corresponding integer (from the set of indexed integers I described above) to c_i as outlined in the epsilon-inequalities I stated. Combining all such integrals gives (n_1)(c_2 - c_1) + (n_2)(c_3 - c_2) + ••• + [n_(k - 1)][c_k - c_(k - 1)] = -(n_1)(c_1) - (n_2 - n_1)(c_2) - ••• [n_(k - 1) - n_(k - 2)][c_(k - 1)] + [n_(k - 1)]c_k. Meanwhile, from a to c_1 you have floor[f(a)][c_1 - a], and from c_k to b you have n_k(b - c_k). If the set is empty, then floor[f(a)] = floor[f(b)] = M. Then the integral is simply M(b - a).
@CoolName04
@CoolName04 2 жыл бұрын
Thanks that was so helpful 👌👌
@Walczyk
@Walczyk 3 жыл бұрын
i like this!! great work
@adrician
@adrician 5 жыл бұрын
Will you ever be doing a video on Lagrange's multipliers?
@alpennyworth8770
@alpennyworth8770 5 жыл бұрын
He made a video on it last year. kzfaq.info/get/bejne/mc5kg7OhxMi1pH0.html
@ilya3458
@ilya3458 Жыл бұрын
Thank you!
@pawansaini78779
@pawansaini78779 4 жыл бұрын
Thanku sir Your video is very supportive Thanks
@Kanha0321
@Kanha0321 5 жыл бұрын
Nice sir
@carlosberrio2906
@carlosberrio2906 4 жыл бұрын
Muy bien resueltas estas integrales
@BassmanRiyadh
@BassmanRiyadh 5 жыл бұрын
Hello, I have a question hope you can make a video about.. the domain an range of (y = (3 - sin(x))^0.5)
@dipesh-singla
@dipesh-singla 5 жыл бұрын
Can you make worksheets on topics like derivate and integral and all other topics with their solution also so people of different country can solve the different type of ques of your country
@yashkrishnatery9082
@yashkrishnatery9082 5 жыл бұрын
Bruh .. !! What a wrist watch.... I've been looking at the watch at half of the time of the video
@omarifady
@omarifady 5 жыл бұрын
Where’s the link of sum of first n square roots ? In the description there’s sum of fist n squares...
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
Fady Omari Exactly what I said. I’ll try to find the link on Google on my own.
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Just added, sorry.
@omarifady
@omarifady 5 жыл бұрын
blackpenredpen Thanks!!
@Uni-Coder
@Uni-Coder 5 жыл бұрын
Unfortunately, there is no exact and finite formula. Only a series.
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
mrbus2007 I saw. There is no exact formula for the of powers of n unless the powers are natural numbers, although even then this formula is still given by an obscure summation involving the Bernoulli numbers.
@mark_tilltill6664
@mark_tilltill6664 4 жыл бұрын
Thank you for two things: That these integrals exist. That with a little courage they can be solved.
@roamlog9129
@roamlog9129 4 жыл бұрын
The last problem can be solved geometrically very easily
@awawpogi3036
@awawpogi3036 5 жыл бұрын
congrats for 200k subs
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Vincent William Rodriguez thank you!!!
@joryjones6808
@joryjones6808 5 жыл бұрын
Do a vid on Euler-Mascheroni constant.
@sankalpmishra1686
@sankalpmishra1686 5 жыл бұрын
you are simply awesome, 💞 from India
@dancifier405
@dancifier405 5 жыл бұрын
Congratulations for 200K subscribers ...😎😎😎🤗🤗🤗🤗🤗🤗🤗🤗#yay......... So please integrate tan(x) from 0 to (π/2) You are like my 1/(1-x) teacher😇😇😇😇😇😇😇😇😇
@arbitrarilyarbitrary8440
@arbitrarilyarbitrary8440 5 жыл бұрын
There’s no indefinite integral that would follow regular integration rules. However I bet you could think of a nice summation to calculate the area for a floor function.
@ZirTaaah
@ZirTaaah 5 жыл бұрын
nice video :) can u try intergral of : sin(x)/sqrt(1+sin(x)*cos(x)
@EternalLoveAnkh
@EternalLoveAnkh 3 жыл бұрын
This is very interesting, but you are doing this by hand. I would like to see a proof of the indefinite integral of the floor function and its powers. Can you do that? RJ
@roamlog9129
@roamlog9129 4 жыл бұрын
We are thinking with respect to x-axis. We can solve more easily Just rotate the screen and think w.r.t. y-axis you can see the last bar root(16) comprises a bigger rectangle whose area is 15×root(16) and then we are subtracting bar of area[ root(1)×1+root(2)×1+....+root(15)] Just rotate
@antaresguitar
@antaresguitar 5 жыл бұрын
2E 5
@angelmendez-rivera351
@angelmendez-rivera351 5 жыл бұрын
Leon Ravenclaw ?
@antaresguitar
@antaresguitar 5 жыл бұрын
@@angelmendez-rivera351 2*10^5
@irwandasaputra9315
@irwandasaputra9315 2 жыл бұрын
1/3 x^3 1/3*4^3 1/3*64 64/3
@JoshuaHillerup
@JoshuaHillerup 5 жыл бұрын
Next do the integral involving the fractional part?
@blackpenredpen
@blackpenredpen 5 жыл бұрын
in that case, we can just change {x}=x-[x] : )
@ssdd9911
@ssdd9911 5 жыл бұрын
halfway there
@419er
@419er 4 жыл бұрын
How would you do 2^X
@bopaliyaharshal2399
@bopaliyaharshal2399 3 жыл бұрын
0 to a ∫ [ x ^(2) ] if [.] Is GIF ( greatest intergel function ) then answer is. ( ( a^(2) - 1)a - 1 ) -summation of r=2 to r= ( a^(2) - 1 ) ∑ √(r).
@bopaliyaharshal2399
@bopaliyaharshal2399 3 жыл бұрын
This is jee main key 😱
@MrConverse
@MrConverse 5 жыл бұрын
But who wins the battle of the integrals?
@leecherlarry
@leecherlarry 3 жыл бұрын
interesting, compi can calculate the battle two: *Integrate[Floor[x]^2, {x, 0, 4}];* *Integrate[Floor[x^2], {x, 0, 4}];*
@aashsyed1277
@aashsyed1277 2 жыл бұрын
hi from sybermath
@leecherlarry
@leecherlarry 2 жыл бұрын
@@aashsyed1277 hi man, all good here, how are you? 😹😎
@leecherlarry
@leecherlarry 2 жыл бұрын
I'm having compi trouble after the OS upgrade from Stretch to Buster. today I'm trying to install old Stretch image... 😨😂
@aashsyed1277
@aashsyed1277 2 жыл бұрын
@@leecherlarry oh dear
@aashsyed1277
@aashsyed1277 2 жыл бұрын
@@leecherlarry fine!
@balazsb2040
@balazsb2040 5 жыл бұрын
But can you do the same with {x}^2 and {x^2}?
@jarikosonen4079
@jarikosonen4079 4 жыл бұрын
I hope to see e^floor(x) and floor(e^x) integrals also...
@entropy4048
@entropy4048 3 жыл бұрын
How do you integrate floor(e^x) from x=0 to x=4??
@jarikosonen4079
@jarikosonen4079 3 жыл бұрын
@@entropy4048 Not sure, maybe finite sum (with a lot of elements). Maybe computer works to make it happen. Integrate from 0 to 1 would be only 2 elements. The x-step positions are x(n)=ln(n) and height is n and summing these rectangles areas: sum (ln(n+1)-ln(n))*n from 1 to 53 + (4-ln(54))*54. This series evaluation looks difficult, but its about 51.6798877368... The series looks it might be "telescoping series", but I didn't try find it in detail. There is actually accurate answer as: 216 - ln(230843697339241380472092742683027581083278564571807941132288000000000000), but not sure how it is evaluated. It looks like some type of factorial (as there is a lot of zeroes at the end)... like 216-ln(54!) As its sum or logaritms, it may turn product inside the ln(). Then it solves, I guess. So if upper bound for integral is "n" the results would be: AREA=n*floor(e^n)-ln((floor(e^n))!). Maybe better question is what is: integ {1-ceil(x)+floor(x)} dx from 0 to +Inf. It could be 'indefinite' or something like -1/12, etc..
@Germankacyhay
@Germankacyhay 2 жыл бұрын
👍
@alainrogez8485
@alainrogez8485 4 жыл бұрын
For the second integral, if n goes to infinity, it seems the result goes to minus infinity. It sounds weird.
@Polaris_Babylon
@Polaris_Babylon 5 жыл бұрын
So, Calc 1 wears Prada Lu?
@kevinpior5265
@kevinpior5265 4 жыл бұрын
I‘ve a question... what’s floor function of 1.9999 period?
@Kanha0321
@Kanha0321 5 жыл бұрын
恭喜,您已达到20万订阅者 今年,您将完成四十万订户的目标。 来自印度的问候 Sorry for mistakes
@blackpenredpen
@blackpenredpen 5 жыл бұрын
Shubham Gupta Thanks. you can just reply in English.
@Kanha0321
@Kanha0321 5 жыл бұрын
@@blackpenredpen I love Chinese language that's why I reply in Chinese
@mathranger3586
@mathranger3586 5 жыл бұрын
e^ln (i)
@arnavagarwal2914
@arnavagarwal2914 3 жыл бұрын
Dude that 4 looks that psi
@zmaj12321
@zmaj12321 5 жыл бұрын
Aww you almost clicked on the problem where I had top solution ;( so close.
@mathematicadeestremo6396
@mathematicadeestremo6396 5 жыл бұрын
I think these are easy....let describe a tough one
@Kanha0321
@Kanha0321 5 жыл бұрын
200k😎😎😎🥳🥳🥳🥳🥳🤠🤠🤠😇😇😇
@user-nl7mn4rr6s
@user-nl7mn4rr6s 5 жыл бұрын
第二題用橫切的比較容易看
@ThinkDifferentlier
@ThinkDifferentlier 5 жыл бұрын
Are these functions even integrable in Riemann sense?
@keonscorner516
@keonscorner516 Жыл бұрын
so integral = sum with floor
@mathematicswithjoy
@mathematicswithjoy Жыл бұрын
Love from India🇮🇳🇮🇳🇮🇳🇮🇳
@safwanahmad3887
@safwanahmad3887 4 жыл бұрын
please can you solve this problem ∬⌊x+y⌋ dx dy 01 0 1
@raymondstheawesome
@raymondstheawesome 4 жыл бұрын
am i the only one who thinks that the answer should be 1 pm but the answer isn't there?
@oscartroncoso2585
@oscartroncoso2585 5 жыл бұрын
First!
@mathssolverpoint6059
@mathssolverpoint6059 5 жыл бұрын
Too easy
@lox7182
@lox7182 2 жыл бұрын
It isn't that hard to find a general formula...
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