TIL about CyberRebate, a dot-com bubble bankruptcy in 2001, whose business plan was to offer technology products at hugely inflated prices (up to 10x suggested price) and then give customers 100% rebates on said items, hoping that around 50% of them would forget to file the rebate form en.wikipedia.org/wiki/Cyb…
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πŸ‘€︎ u/a3poify
πŸ“…︎ Dec 17 2021
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I believe humanity is a product of alien creation and that's one of the BIG reasons the governments haven't disclosed the truth... Hundreds of hours of research,reading, listening and connecting dots and testimonies to best create a mosiac of truth. But is it a hard pill to swallow. As is all truths

I for the past couple months have been doing some intense researching and studying on this topic. I realize if someone is an average believer in UFO's they most likely will think the basics. Roswell happened. We recovered crafts and aliens. And that's about it and that the government is keeping it secret.

But it goes WAY DEEPER then I ever imagined. And I think most of us who have done our due diligence know that aliens and consciousness are linked on many levels. Along with what may be alternate dimensions and dimensional entities as well. From Geaorge Knapp and Jeremy Corbells research and findings to David Fravor and his sightings to Bob Lazar and then what I think is the treasure trove of info on this subject is what Dr Steven Greer is doing. Now I get that not everyone believes in Greer or is thrown off by the fact he talks about remote viewing, summoning craft with your conscious and other stuff. While we can debate those topics (ones I've found myself now being much more open minded about the ever before)

What's undeniable is the amount of eye witness testimonies he has from top ranking officials for the CIA, DIA, FBI, Pentagon, Area 51 whistle blowers and people who were at REF Goodrich and so forth. If you haven't I HIGHLY suggest you check these out. Many of these people seem highly credible and don't seem to be bullshitting what so ever. This is not a game. This is not a joke this is as real as it gets and from what I've gathered even more "real" then real itself.

Once you start hearing the same reports and info out of several sources not even linked to one another. These people are verifying others with tjier testimonies like Bob Lazar. At this point Bob wasn't lying. S4 definitely exists. Alien aircraft are definitely at area 51. And that seems fact at this point.

Things I've gathered from multiple people corroborating the same info.

  1. The moon is not what we think it is. And has alien bases on it. And when Armstrong and Aldrin went to the Moon these aliens were there watching us take our first steps.
  2. Mars also has alien bases on it. And the Mars "face" they tried to say was just shadows is not. And was made by another alien race.
  3. Us government has re-engineered these crafts and are easily mistaken for real ET's. Scary to think about how they could use that in so many ways.
  4. There are WAY more then just 1 alien species. Now this is one I have heard many different numbers on. I don't think anyone knows exactly. But I've heard
... keep reading on reddit ➑

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πŸ‘€︎ u/CDogTheGod
πŸ“…︎ Oct 21 2021
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Is the dot product the quickest way to find if two vectors are orthogonal?

I ask that because my book frequently asks to do something it wasn't in any lesson before it. So far this is the quickest (if not only) way that I know if two vector are perpendicular to each other.

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πŸ‘€︎ u/oldespondent
πŸ“…︎ Jan 05 2022
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I was just editing this music video and noticed on my final "product" that on that one frame 3 black dots appear, in every media player. But then i imported it back to Resolve and the dots are just not there. I have no idea how to fix it... So my question would be; what the hell is this and why? reddit.com/gallery/rogo3o
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πŸ‘€︎ u/Atesz_Z3TA
πŸ“…︎ Dec 25 2021
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Taking dot product of vector that has a normalisation factor

I'm trying to verify that a given vector, u, is normalised

I understand that if this is the case, then the dot product of u with itself should be 1

However, I'm not sure how to do this if my vector has a normalisation factor, eg, u = 1/6(6i, 7)

How would I take the dot product of this?

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πŸ‘€︎ u/OnceAponASecret
πŸ“…︎ Jan 06 2022
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defective product? superbuy said my product is defective but i cant see anything wrong. is it the two black dots? (one on the pocket and one near the seam (r they holes?))
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πŸ‘€︎ u/Ryce-_-
πŸ“…︎ Dec 22 2021
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[orbital mechanics] can't figure out how to derive dot product identity.

I'm having difficulty, enough to be embarrassed, figuring out how a dot product identity is derived. Vectors are in brackets btw. [r]β€’[r'] = r*r' where prime is the derivative wrt to time. I know the identity [r]β€’[r] = r^2 but can't figure this one. Can someone please help or point to a good source for this. My googling is unhelpful

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πŸ‘€︎ u/MrDirtyMeat
πŸ“…︎ Nov 30 2021
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bought this lighter from eBay, want to know better if it’s authentic. eBay listing β€˜ST DUPONT Gold Plated Lighter - Ligne 2 model. Genuine product. Vintage serial number K9BD51 Excellent Condition overall. Needs Gas. Gold dot inside refill stopper. Has initials MV lightly engraved. β€˜ reddit.com/gallery/ranb5g
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πŸ‘€︎ u/Kaymon7
πŸ“…︎ Dec 07 2021
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[Functional Analysis] Maximization of Dot Product Over a Closed, Bounded, Convex Set

I'm currently reading this paper (http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.297.8841&rep=rep1&type=pdf) on invariant sets for PDEs and am confused by an argument in Lemma 1. Hopefully you can access the paper, but if not I'll try to make my question self contained.

Essentially, you have a function U:Rn x R β†’ Rm, U: (x,t) β†’ U(x,t) that's a solution to a system of PDEs on the domain D x [0,T]. It is assumed that U(x,t) is unique and is also continuous everywhere in D x [0,T]. Importantly, up to time t*, the set {U(x,t):(x,t) ∈ D x [0,t*]} is contained inside a closed convex set Sp βŠ‚ Rm and there is a special point (x*,t*) with the property that U(x*,t*)βˆˆβˆ‚Sp .

At one point in Lemma 1 of the paper, they consider the function pβˆ™U(x,t) where p is the outward normal vector to the set Sp at the special point U(x*,t*). The paper argues that "since Sp is convex, the function pβˆ™U(x,t) attains its maximum value in D x [0,t*] at (x*,t*)." "Therefore at (x*,t*):

pβˆ™βˆ‚U(x,t)/βˆ‚t β‰₯ 0, pβˆ™βˆ‚U(x,t)/βˆ‚xi=0 i=1,...,n, and pβˆ™βˆ‚^2U(x,t)/βˆ‚xiβˆ‚xj is negative semidefinite.

Broadly speaking, I understand where the argument comes from. Namely, the dot product is a linear (convex and concave) function and hence a maximum is going to be obtained on the boundary of a convex domain. Moreover, the three derivative conditions come from necessary conditions for optimality and from properties of the Hessian matrix at a maximum. Where I'm having issues though is that the function is nested. So while the range of U is a subset of the convex set Sp, it need not be convex itself, and hence those optimality conditions need not apply. Also, supposing those conditions did hold, if the x* where the maximum occurs is on the boundary of D, directional derivatives are not going to be defined in every dimension. So the second condition of pβˆ™βˆ‚U(x,t)/βˆ‚xi=0 could fail as well.

Sorry for the long post, but any clarification that you can offer would be great. I get the impression I'm missing something obvious because the paper goes over these points so quickly, but I can't seem to find something that clears things up.

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πŸ‘€︎ u/LeifEricsonDay
πŸ“…︎ Dec 10 2021
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Dot Product - Laurent Rosenfeld blogs.perl.org/users/laur…
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πŸ‘€︎ u/liztormato
πŸ“…︎ Dec 27 2021
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Spent an hour making the Field Of View script for NPCs, only to find out that dot product is a thing :(
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πŸ‘€︎ u/coolchris4200
πŸ“…︎ Sep 25 2021
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In Search of a Better Dot Product github.com/Carbocarde/Vec…
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πŸ‘€︎ u/Carbocarde
πŸ“…︎ Nov 12 2021
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[Product Question] Peace Out Acne Dots: How to Apply?

Hi! Typically, when I apply these dots, they’re for pimples that are either under the skin or have already been popped. My face broke out recently and I currently have one that has come to a head. I’m wondering if I should pop it, then apply the sticker? Or will it still work without popping it?

Hopefully my question made sense.. basically, I don’t want to pop any pimples (because that’ll slow the natural healing process), but I’d also like the acne dots to be as effective as possible. :’)

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πŸ‘€︎ u/lookpenguins
πŸ“…︎ Nov 28 2021
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Dreamt I was being chased by people in purple polka dot gas masks and a strangely named product.

It was called Nemesis Hades cake. It was like a cross between a pannettone and mochi. Found it in an abandoned asian grocery market.

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πŸ‘€︎ u/SightWithoutEyes
πŸ“…︎ Dec 22 2021
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NEW! When a product designer starts working at DoT…
πŸ‘︎ 80
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πŸ“…︎ Oct 21 2021
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How do I enter/edit vectors u and v to find the dot product?
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πŸ‘€︎ u/Hoowem
πŸ“…︎ Nov 08 2021
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Optimal Matrix Dot Product Calculation

I'm writing code for an Arduino and I need to multiply many matricies (the matricies are 4x4 homogeneous matricies) very quickly. Here is the code I have so far.

  void matmul(const float mata[4][4], const float matb[4][4], float prod[4][4]) {
    float sum_ = 0;
    for (int i = 0; i < 4; i++) {
      for (int j = 0; j < 4; j++) {
        prod[i][j] = 0;
        for (int k = 0; k < 4; k++) {
          sum_ += mata[k][j] * matb[i][k];
        }
        prod[i][j] = sum_;
        sum_ = 0;
      }
    }
  }

So is there a way I can multiply two matricies together more efficiently?

Solution

I followed u/S-S-R's advice and hardcoded it.

    void matmul(const float A[4][4], const float B[4][4], float C[4][4]) { 
  
   /*  
   * This function will multiply two of the homogeneous matricies and the product write onto the variable: prod[4][4]
   *  It is hard coded as the matricies will be constant and it is more optimal than using loops
   * 
   *  --example--
   *  A = [[1,2],[3,4]]
   *  B = [[1,0],[0,1]]
   *  
   *  dotProduct = [[1,2][3,4]]
   *  
   *  --see also--
   *  https://www.mathsisfun.com/algebra/matrix-multiplying.html
   *  https://www.youtube.com/watch?v=dQw4w9WgXcQ  <-- This helped me the most out of everything
   */
   
    C[0][0] = A[0][0]*B[0][0] + A[0][1]*B[1][0] + A[0][2]*B[2][0] + A[0][3]*B[3][0];
    C[0][1] = A[0][0]*B[0][1] + A[0][1]*B[1][1] + A[0][2]*B[2][1] + A[0][3]*B[3][1];
    C[0][2] = A[0][0]*B[0][2] + A[0][1]*B[1][2] + A[0][2]*B[2][2] + A[0][3]*B[3][2];
    C[0][3] = A[0][0]*B[0][3] + A[0][1]*B[1][3] + A[0][2]*B[2][3] + A[0][3]*B[3][3];
    
    C[1][0] = A[1][0]*B[0][0] + A[1][1]*B[1][0] + A[1][2]*B[2][0] + A[1][3]*B[3][0];
    C[1][1] = A[1][0]*B[0][1] + A[1][1]*B[1][1] + A[1][2]*B[2][1] + A[1][3]*B[3][1];
    C[1][2] = A[1][0]*B[0][2] + A[1][1]*B[1][2] + A[1][2]*B[2][2] + A[1][3]*B[3][2];
    C[1][3] = A[1][0]*B[0][3] + A[1][1]*B[1][3] + A[1][2]*B[2][3] + A[1][3]*B[3][3];
    
    C[2][0] = A[2][0]*B[0][0] + A[2][1]*B[1][0] + A[2][2]*B[2][0] + A[2][3]*B[3][0];
    C[2][1] = A[2][0]*B[0][1] + A[2][1]*B[1][1] + A[2][2]*B[2][1] + A[2][3]*B[3][1];
    C[2][2] = A[2][0]*B[0][2] + A[2][1]*B[1][2] + A[2][2]*B[2][2] + A[2][3]*B[3][2];
    C[2][3] = A[2][0]*B[0][3] + A[2][1]*B[1][3] + A[2][2]*B[2][3] + A[2][3]*B[3][3];
... keep reading on reddit ➑

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πŸ‘€︎ u/Emnizate
πŸ“…︎ Oct 29 2021
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Took my old Epi Studio DOT and threw some Duncan Invaders in it, then used racing stripe vinyl from Amazon. Happy with the final product. Thing friggen rips with those pickups.
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πŸ‘€︎ u/bradleyd1992
πŸ“…︎ Oct 01 2021
🚨︎ report
Recently ordered some tints from this brand called Anour and received them today. The pink shade looks in questionable condition. Is that mould on my product? Also the nude shade looks like it has some uneven texture like dots on it. (ps. These are untouched, i literally just opened them) reddit.com/gallery/qwhyz0
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πŸ‘€︎ u/ishita_xoxo
πŸ“…︎ Nov 18 2021
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When discovering the dot product, did they come up first with a * b = ax * bx + ay* by or a * b = |a| * |b| * cos(theta) ?

I know it's a weird question, but... how did they know that multiplying the x and y values of each vector together would give the same value as this formula a * b = |a| * |b| * cos(theta)?

I mean, i know geometrically how to get to that formula and how it works, but i can't wrap my head around how ax * bx + ay * by gives the same result as |a| * |b| * cos(theta)...

What is the intuition behind a*b = ax * bx + ay * by?

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πŸ‘€︎ u/Final_Bend8651
πŸ“…︎ Oct 25 2021
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[Skin Concerns] possible keratosis pilaris, but only with red dots - skin is smooth. Does anyone else struggle with this? Typical KP products only seem to help people with bumps
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πŸ‘€︎ u/rainonrose
πŸ“…︎ Aug 28 2021
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Does any know how the vector dot product rule is derived?

I'm currently taking a statics course and understand what dot products are, I'm just curious where the formula PQ= |P||Q|cos( ΞΈ ) comes from.

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πŸ‘€︎ u/Mr_Donut1672
πŸ“…︎ Sep 23 2021
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First quilt done! Dual Dino prints for my 3 year old. The border rippled on one side but I feel pretty good about the overall product. That back is just solid lime minky dot.
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πŸ‘€︎ u/RunningHood
πŸ“…︎ Sep 22 2021
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