A typical boom stand has three points of flexibility and a rotating base. Those three points are all in-line with each other though, such that the entire range of the boom stand with the base at some arbitrary fixed angle exists as a plane.
I'm wondering if there exists a desk-mounted boom stand where the joints are ball-joints, double joints such that there are six total joints and each pair is orthogonal to each other, or at the very least such that the middle joint is perpendicular to the others. This would allow for the boom stand to be bent outside of the plane.
I hope I'm being clear about what I'm looking for. Thank you.
I wrote a similar post to this a few days ago, but it was removed because I was “asking for medical advice”, so let me try to out this another way.
Was hoping somebody could give me some more insight into atlas orthogonal. I asked this in another sub, but hardly anybody knew this sub field.
Had three atlas orthogonal adjustments, but it made my neck pain worse. Ironic, considering I didn’t go to AO for pain in the first place but I did have some neck pain, but it was significantly lower than what I experience now.
The chiro took pre adjustment and post adjustment x-rays. Of course pre adjustment he showed me how straight my neck looked, but after one adjustment showed me how much more curved my neck looked. I’m no doctor, but I thought the bones were a lot stronger than we give them credit for..? I just can’t imagine my neck going from straight (I think he called it “military neck”) to curved in the span of one adjustment.
These are quieter. That's their entire thing.
Me & Atlas Orthogonal
I sought out AO for these reasons:
-I had multiple physical traumatic injuries that involved impact to the left side of my body and concussions
-I have these symptoms: Chronic neck, pelvis and back pain, loss of hearing in left ear, short leg, imbalance, chronic head tension, neurological symptoms (fatigue, lack of focus), weird liver and hormone levels
I already tried these things: changing diet, nutritional supplements, getting 8 hours of sleep per night, vestibular therapy, hyperbaric oxygen treatment, massage, physical therapy, psychotherapy, other chiropractors
I found my AO because my functional neuro chiropractor said my atlas was "jammed up" and continued doing very physical neck adjustments on me. I wanted a gentler approach to neck adjustments.
At 31 it is time for some answers as to why I can't work full time and have been in chronic pain for the past 3 years after my concussions.
I recently received upper cervical x-rays and I have an atlas subluxation. The first x-ray revealed I was off from neutral by 3.14 degrees. I have had one adjustment where the AO corrected it by one degree. Its been a week, I feel more of a difference in a short period of time than anything I've tried so far.
I won't bother you with the details of how horrible the symptoms of post concussion and atlas misalignment are, how soul crushing finding answers for chronic injury are when you don't have them, but after time, money and research I found atlas orthogonal and want to share this process with those who are curious.
Here is what I'm learning
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The atlas orthogonal procedure is painless but symptoms can flair up right after the adjustments.
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"Holding the adjustment" is a delicate art. The body's attempt to understand why you're messing with the atlas. My AO did a good job of explaining that this adjustment is a novel experience for the nervous system, and that symptoms can occur as our body tries to make sense of the shift (my words, not his).
My AO gave me recommendations for how to hold the adjustment:
-*avoid full neck extension for the first few weeks of the treatment, sleep on a pillow that allows for neutral spine, park the car backwards into the parking spot to avoid full neck extension when pulling out after receiving adjustment, avoid LEVERAGE on the head (hand on head leaning on couch, sitting in chairs), be careful getting hugged by people taller than me, avoid fun yoga poses that you w
... keep reading on reddit ➡EDIT: I think I may have sorted it out, see this post on Eng-Tips for a further discussion and excel file demonstration: Rigid Diaphragm Analysis with Non-Orthogonal Walls - Structural engineering general discussion - Eng-Tips
This is a long shot but does anyone know of or have a PDF of the reference document shown under the "analysis procedure" heading here: Calculation Modules > Miscellaneous Calculation Modules > Torsional Analysis of Rigid Diphragm (enercalc.com)
Alternatively does anyone have any good references for generalized rigid diaphragm force analysis, every source I've been able to muster up addresses orthogonal resisting elements only which makes the computation for center of rigidity trivial.
Thanks in advance.
Edit: Diagram of system
https://preview.redd.it/pqbuw3safv981.png?width=662&format=png&auto=webp&s=c9b849bcb1749fd226a63906272f7ad6e555698c
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.
I was reading through The Physics of Musical Instruments (Neville H. Fletcher and Thomas D. Rossing) and got to a section using perturbation theory to find first order corrections from deviations in the bore of a flute/horn. (Section available here: https://imgur.com/a/2ur9QSF ). It's been a few years since I've really done much perturbation theory (and that was in a quantum setting no less); why is the base solution p0 and the first perturbed solution p1 functionally orthogonal?
I am creating a game rendered in orthogonal mode. I have a directional light set to cast shadows on the ground. Shadows cast on the human characters below, however, are too big. These meshes have a custom material with a cel shader and a next pass outline shader. Interestingly, the sphere below, without a custom shader material, casts normal shadows, leading me to believe that the problem has to do with my custom shader material. Does anybody have a clue what is going on? I have included the shadow settings for the directional light below. Thank you.
In-game screen grab of large shadows
Easy way to test is create a 3D root node, add a MeshInstance with a cube mesh, add a camera, set to orthogonal, set size to about 10, set translation to (10, 10, 10), set rotation to (-45, 45, 0). Starting the scene, the cube will be way off center.
Intuitively, I feel like since the polar position is opposite the rotation (or however it works), it should point at the origin (though CMIIW). My only guesses for why this happens are that the camera is not a plane or it is not centered, but I am not sure how to fix either dynamically.
Hello! I graduated from college in 2018 with a bachelors in CS, so a lot of these things are kind of confusing to me as I lost my familiarity with some things.
First question, what do the symbols here mean? Specifically <f,g>, the dash over f(x), L(base 2), the || around f(base n) such as ||f(base n) ||
https://en.wikipedia.org/wiki/Orthogonal_functions
Follow up question is what is John trying to show in his example? Can some one explain what he is doing?
And lastly, falling down the rabbit hole someone suggested to look up Sturm-Liuville Theory (top comment), what is this and what is the connecting being made?
https://www.reddit.com/r/learnmath/comments/n1oivl/why_do_we_want_an_orthogonal_basis/
Apologies if the answer is to long to make a comment on. I understand orthogonality is the dot product of two vectors to be 0, but I don't understand what the calculations above are showing, why don't they end up as zero? Maybe a better question is how to I read math examples like these so I can understand them? Is it me or is it just hard to read the examples? I feel like the more I look into it the more confused I get.
I've got a set of orthonormal (and monic) polynomials that I generated using the well known three term recurrence relation. When I plot the functions, the interval upon which they are orthogonal is obvious. However I don't know how to determine an appropriate weighting function to use for the inner product. (The polynomials do not match any of the classic or well described functions as far as I can tell.) How does one typically find the weighting function? BTW, just an amateur math enthusiast here, so I probably won't understand anything beyond undergraduate level math.
I was given u=[1 1 2 6] 4*1 vector, and subspace W=Col[1 1 5, -1 2 1, -1 1 -1, 2 -1 4] a 4*3 matrix. I am confused by the Col notation. Typically to do this problem I would find the RREF of the given matrix, which would tell me the pivot columns that would be the basis. I would use the basis to make the matrix C. Then I would solve for Pw=C(C^(T)C)^(-1) C^T.
What I did is took the rref of [1 1 5, -1 2 1, -1 1 -1, 2 -1 4], then I found the basis or my C matrix to be [-3 -2 1]. I was able to factor 1/7 out of the Pw I calculated, but the book answer says it should be
1/33 [22 11 0 11, 11 19 9 -8, 0 9 6 -9, 11 -8 -9 19].
What am I doing wrong?
I know it is, but I don't understand this proof.
What does (u,c1v1+c2v2) mean?
This review consists of two parts: an overview with marked spoilers and unmarked mild thematic spoilers to help potential readers decide if this work is right for them, and a more in-depth analysis, which contains unmarked moderate spoilers for Orthogonal.
#Overview
Tenet: Don't try to understand it, feel it.
Me: Oh come on, Nolan. That's just lazy, now. You call this sci-fi? You know you can't just slap some vague technobabble on it and call it a day, right? I hate how so much science fiction feels the need to dumb it down for the masses. What's the point of hiring renowned physicists to consult on your movies if you end up with scenes where your pilot has to have wormholes explained to him when he's literally in sight of the one he's about to fly through? I wish there was something out there that puts in some actual effort in the worldbuilding, something smart. Something that doesn't treat its audience like idiots. Such a shame, too. Inverted matter looks really cool.
Monkey's paw: *curls*
...
Well, the good news is, I found a story like that. The bad news is, having read it, I now feel like an idiot.
Welcome to the world(s) of Greg Egan, who puts the 'hard' in 'hard science fiction' in more ways than one.^1 He's the author of works such as Permutation City and Sqchild's Ladder, which are considered some of the hardest science fiction novels ever. But while those are set in more-or-less our world, Egan's most valuable contribution to the genre (at least, in my opinion), is his alternate universes, which run on different laws of physics from ours.
Orthogonal is a trilogy of novels (The Clockwork Rocket, The Eternal Flame, & The Arrows of Time; roughly 1100 pages total) set in one such universe. I chose it as my first Egan work to read largely because of its concept, which was just too intriguing for me to resist. From the blurb on the website:^2
>In Yalda’s universe, light has no universal speed and its creation generates energy.
>On Yalda’s world, plants make food by emitting their own light into the dark night sky.
>As a child Yalda witnesses one of a series of strange meteors, the Hurtlers, that are entering the planetary sys
... keep reading on reddit ➡Given: u=[3 4] a 2 x 1 vector
y=-x
I know that z= u-w and that w =((u*v)/(||v||squared))*v
I know that the answer is w = 1/2 [-1 1], so I think that [3 4] * some value over 2 (because the answer includes 1/2) I can play around with numbers, but then I won't know how to get to the actual answer. How do I find v? In all the book examples v is given, so I'm pretty lost
I am barging into a community that I don't know about a topic that I know (almost) nothing about, please forgive me for that.
For a project I am looking for software that can stitch a map from a video on a plane flying in a straight line, camera looking straight down. There is no other information than the video (and seperately recorded data like altitude and bearing).
Does such software exist, or something that comes close and is Open Source so it can be adapted?
Or do you know about a series of operations that could lead to the same required result: a stitched map of considerable larger size than one individual frame of video captured from the plane?
Given a curve on a 2d surface in 3d is there a name for the coordinate system compriesed of the normal, tangent vectors and the vector positively orthogonal to the tangent and normal vector?
Also if theres a name for the vector positively orthogonal to the tangent and normal vector I keep thinking right hand rule but I don't think thats the name of the coordiate system.
So suppose we have a surface in 3-space, and are given the generalized parametric from of the surface as R(u,v)=(x(u,v), y(u,v), z(u,v)) and also has a level surface f(x,y,z)=1. Show that grad(f) is perpendicular to the tangent vectors (partial derivatives) dR/du and dR/dv.
I was given a hint that the question is an application of the chain rule and implicit differentiation.
I started by first taking the general derivatives to obtain (all partials) dR/du=(dx(u,v)/du, dy(u,v)/du, dz(u,v)/du), likewise for dR/dv, and grad(f)=(df(x,y,z)/dx, df(x,y,z)/dy, df(x,y,z)/dz). And the idea that perpendicular vectors have a dot product of 0.
Naturally I began with taking the dot product of the two
=dx(u,v)/du * df(x,y,z)/dx +dy(u,v)/du *df(x,y,z)/dy+dz(u,v)/du*df(x,y,z)/dz
As is this does not simplify to 0. So I begin exploring the idea of implicit differentiation. The problem i arrive at is if I implicitly derive, for example, df(x,y,z)/dx, I end up with more partials regarding x,y, or z. and doing so for dx(u,v)/du we get more partials regarding u and v. Nothing seems to cancel since the parametric form is not in terms of x,y,z variables and f(x,y,z) is not in terms of u,v variables. I just get longer, more complex equations that do not cancel.
I then took to the idea that the cross product of dR/du and dR/dv should be parallel (or opposite parallel) to the gradient, but again I arrive at a long string of partials that do not cancel and are of 5 different variables.
I have been on this for almost 9 hours now and have made no progress.
From Nick Bostrom's Superintelligence, and derivatives thereof, we have a set of thesis about how various degrees of intelligence may behave based on various forms of goals.
From https://link.springer.com/article/10.1007/s11023-012-9281-3
" The first, the orthogonality thesis, holds (with some caveats) that intelligence and final goals (purposes) are orthogonal axes along which possible artificial intellects can freely vary—more or less any level of intelligence could be combined with more or less any final goal. The second, the instrumental convergence thesis, holds that as long as they possess a sufficient level of intelligence, agents having any of a wide range of final goals will pursue similar intermediary goals because they have instrumental reasons to do so. In combination, the two theses help us understand the possible range of behavior of superintelligent agents, and they point to some potential dangers in building such an agent. "
The definition for orthogonal matrix is A^(T)A=AA^(T)=I
My question is if it's necessary to show that both A^(T)A and AA^(T) equal to I, or is one enough and why?
