user8469759

general recent conversations

$Mathematics$ Discussion on answer by A.Γ.: Quasi-n…

Imported from a comment discussion on math.stackexchange.com/q...

user8469759

Nov 6, 2024 23:30

Does this technique of solving a Least Squares problem have a name? Just like the QR factorization can be used to efficiently solve an LSE problem I wonder if this procedure of yours has a general name.

$Mathematics$ Mathematics

Associated with Math.SE; for both general discussion & math qu...

user8469759

Jul 5, 2024 13:08

Hi, can anyone tell me the meaning of $\rightarrow$ in the context of $\exists x (\phi(x) \wedge \forall y (\phi(y) \rightarrow y=x))$.

As mentioned in the question: https://math.stackexchange.com/questions/228285/how-can-i-get-the-negation-of-exists-unique-existential-quantification

user8469759

May 11, 2022 10:37

As I think is also a math question

user8469759

May 11, 2022 10:36

Q: Error in equation 2.1. in Ray Tracing Volume Densities

I am reading through Kajiya - Ray Tracing Volume Densities paper. And I've already got stuck into section 2. I wonder if there's a mistake in that equation. I'll quote the relevant bit The quantity to be calculated in a scattering problem is the energy per unit solid angle per unit area $$ dE = ...

user8469759

Apr 24, 2022 19:45

I can migrate the question to mathexchange but I thought it was more suited for computer science

user8469759

Apr 24, 2022 19:44

and tell me whether or not the proof I gave is correct

user8469759

Apr 24, 2022 19:44

can anyone if have time have a look at this question? cs.stackexchange.com/questions/150971/…

user8469759

Feb 22, 2021 09:12

Hi guys, does anyone know if there's a way to use the Conjugate gradient to perform the inverse of a symmetric positive definite matrix?

MathOverflow

General discussion for mathoverflow.net

user8469759

Nov 17, 2023 06:16

Hi all. I am not too familiar with the math research literature. I wonder if there's any journal or conference where new riemmanian manifolds and their retraction calculations are published. I often seen manifolds like Compact Stiefel and QR factorization as retraction, but I wonder if there's a research area whose focus is to find new manifolds and calculating their retractions.

Discussion on question by user8469759…

Imported from a comment discussion on workplace.stackexchange....

user8469759

Sep 1, 2023 23:57

@joeqwerty pretty sure if I ask you (for example) to implement a matrix vector multiplication (which has known complexity) but you overcomplicate it that's an obvious problem... if you give me code where a function to perform A actually does B that's also a problem. If your code has 0 documentation/comments that's also a problem. I am not aiming for perfection. Just few basics where everyone would agree would make the code better and more maintainable.

user8469759

Sep 1, 2023 23:57

They do and I quote "In project X we had an incredible amount of technical debt".

user8469759

Sep 1, 2023 23:57

Around 1 year and a half.

user8469759

Sep 1, 2023 23:57

I don't wanna start a massive debate.. but working with discipline is necessary to deliver the product the customer asked... no disciplines puts actually at risk project deliverable, I say this from experience. We had a employee who was the only one who knew his code and it was considered for commercial product. However it was so badly written we had to ditch the all code and start from scratch that feature. All I am doing in my question is separating the two points cause they're related but I am focusing on a specific one. This is not personal but just common sense...

user8469759

Sep 1, 2023 23:57

@TymoteuszPaul it is my priority... but that's not the point of the question...

Discussion on answer by David Scarlet…

Imported from a comment discussion on fitness.stackexchange.co...

user8469759

Sep 1, 2023 13:31

Isn't benching too often counter productive? And how many would you suggest (per week)? 2 you said "only" which sounds like not enough. But given that you should rest a specific muscle group at least 1 day I don't think doing more than 3 times eventually is a good idea.

user8469759

Sep 1, 2023 13:31

@DavidScarlett not gonna lie... but you're answer depresses me a bit.

user8469759

Sep 1, 2023 13:31

I don't wanna lift heavier. I want to have more volume given the current weight I can maximally lift at the moment. I don't think this answer matches exactly my question.

Discussion on answer by TheDemonLord:…

Imported from a comment discussion on workplace.stackexchange....

user8469759

Jul 30, 2023 04:14

In my opinion anyway code readability / maintanability is as important as the business case. In my experience if the code is completely unreadable it just makes your life harder.

The h Bar

General chat for Physics SE (physics.stackexchange.com). For M...

user8469759

May 11, 2022 10:46

As I think there's some physics in there, you might be able to help

user8469759

May 11, 2022 10:46

Q: Error in equation 2.1. in Ray Tracing Volume Densities

mathematics volumetric-scattering

The Whiteboard

General Discussion for softwareengineering.stackexchange.com P...

user8469759

Feb 1, 2021 16:08

Q: clBlast Implementation of xaxpy

I'm trying to learn more about how to implement Linear Algebra routines in OpenCL. I came across clBlast whose kernels implementation I think should answer my question. However I don't understand the rationale behind having for example in xaxpi for example. There're several versions and I don't u...

math parallel-programming high-performance opencl

$Mathematics$ Discussion between user8469759 and prash

Imported from a comment discussion on math.stackexchange.com/q...

user8469759

Jan 21, 2021 17:50

I might be onto something, if it is of any interest please get in touch

user8469759

Jan 21, 2021 15:50

Stupid question, if your transformation is derived by a markov chain I guess it has special properties right? I guess you either have a transition matrix or a transition kernel which very specific properties that might actually make the proof simple.

user8469759

Jan 19, 2021 15:10

I mean given what you read (variational analysis) I guess you probably know better than I do that the subdifferential is somewhat meaningful in when the operator is not linear.

user8469759

Jan 19, 2021 15:09

but I can't see how to use my hypothesis explicitly

user8469759

Jan 19, 2021 15:08

So you write $Ax = b$ you write $x$ as function of $b$ using the Cramer rule, you pick the difference between $x_{i+1}$ and $x_i$

user8469759

Jan 19, 2021 15:07

yes, it is a subdifferential. However given the nature of my problem I think you might want to consider the finite difference simply (which is essentially what I'm doing with Cramer really)

user8469759

Jan 19, 2021 14:55

however I think you can derive a condition for my problem by applying the Cramer Rule to the system.

user8469759

Jan 19, 2021 14:54

The interpretation I'd give to the monotone operator is that once you apply it you obtain a new vector whose dot product is positive (this is by definition) but then you can relate this to angles.

user8469759

Jan 19, 2021 14:51

I'm actually still interested in that problem I'd like to know if there're conditions

user8469759

Jan 19, 2021 14:51

Hello, I moved to a chat as it's a bit easier.

user8469759

Jan 19, 2021 14:45

What is wrong with the definition I gave? I think it's intuitive, or do you mean a formal one from literature?

user8469759

Jan 19, 2021 14:45

Well if $A$ is diagonal with positive entries the monotonic behaviour won't change, indeed I was asking for condition / constraints on the matrix $A$ to preserve such behaviour. I came across monotone operators and I thought they might be related, but I haven't investigated this since. How come you're looking into this?

user8469759

Jan 19, 2021 14:45

I never was unfortunately

$Mathematics$ Discussion between user8469759 and ε-δ

Imported from a comment discussion on math.stackexchange.com/q...

user8469759

Jul 21, 2020 10:53

I need to re-visit your answer with this conversation on hand

user8469759

Jul 21, 2020 10:53

I think so... I think I got confused for something silly.

user8469759

Jul 21, 2020 10:51

actually never mind, please carry on

user8469759

Jul 21, 2020 10:50

before you carry on

user8469759

Jul 21, 2020 10:49

it's a basic fact. If $A$ has empty interior then the X\A is dense

user8469759

Jul 21, 2020 10:49

I think so, isn't this a way to justify why Baire's theorem is called Category theorem

user8469759

Jul 21, 2020 10:45

I guess I can prove that identity at some point as exercise

user8469759

Jul 21, 2020 10:43

ok I didn't know that relationship

user8469759

Jul 21, 2020 10:41

if $X_n$ is closed and has empty interior and I wanted to show that $X_n^c$ is dense in $X$ then I need to show that for any $U$ open in $X$ the intersection $U \cap X_n^c$ is not the empty set.

user8469759

Jul 21, 2020 10:39

first of all, the way I was trying to prove this was the following

user8469759

Jul 21, 2020 10:39

I do apologize

user8469759

Jul 21, 2020 10:39

hi!

user8469759

Jul 21, 2020 10:22

if not just give me a time to catch up on this, if you are available of course

user8469759

Jul 21, 2020 10:21

Hi, are you available for a cht?

user8469759

Jul 21, 2020 10:21

Not really, sorry.

user8469759

Jul 21, 2020 10:21

Is $A$ supposed to be some $X_n^c$ as a starter?