#computational physics

[astrocatfizziks]

Love this library :)

pip install smplotlib

[maxwells-daemon]

nothing like developing a hyperfixation when I should be doing so many other things

[teledyn]

Could the Universe be a giant quantum computer?

“I think if he had had a more conventional education, if he’d come up through the ranks and had taken the standard physics courses and so on, maybe he would have done less interesting work.”

[aromanrom]

Quantum Computing Simulator

Introduction There is a ‘new’ repository on GitHub1. It’s not that new, I think I started it in September 2022, but I didn’t add any description on it here. So, here it is now: A quantum computation project. It’s a quantum computing simulator together with many algorithms as examples and tests. It started first as a very simple simulator, one that simply followed the math, with matrices, tensor…

[learnsharewithdp]

How to Use Global Variables in Fortran (Modern Way)

If you’re coming from languages like C or Python, you might wonder: how do I declare global variables in Fortran? In modern Fortran (90 and later), the recommended approach is to use modules. These allow you to define shared variables accessible across multiple program units—just like global variables. ✅ Recommended: Use a Module Here’s how to define and use global variables using a…

[andranikfakirian]

Current Projects

After so much time of silence, I feel the necessity to report about the past and current situation. I'm sorry if it seemed to you that I've abandoned the blog idea. I didn't forget it, I just couldn't find enough time to start publishing again. But now I'm determined to come back with news. And I definitely have a content to tell you.

And the first will be the satellite project. Honestly, we still haven't finish it, and I'm not sure if I have time to continue the work right now. Therefore, there won't be many updates about this project at the moment (if there are any at all). We do have some results for our assessment for Data Analysis subject, so we obtained some good grades. But I'll do my best to continue working when I'll find enough free time to do so. And yes, when I say "we", I am not mistaken. This project is being conducted by me and my partner. I'll introduce him if he doesn't mind.

P.S.: Here's the performance of our model. The first image is a satellite photo, the second - ground truth mask image, the third - prediction made by our not enough trained model.

The second will be the computational mathematics project. I have reached a milestone in the form of an almost beta version of the software package. The solver with automatic timestep sampling has already been created and works pretty well. It's still not really optimized but it's already useful and precise. There's still enough space fpr research and testing the algorithm, so it's possible to obtain in the near future enough material to make a publication in a scientific journal.

P.S.2: Here you can see the difference in performance of two algorithms: explicit RK4 (the upper image of unstable solution) and mine implicit (m, k)-method with autostepper (the lower image) - for the same problem.

[myc0l0gy]

taught myself to solve coupled differential equations with an actual library instead of hand writing the numerical methods like I had to do in my computational physics class last semester

[jack85200]

Read the article here!

CFD Analysis And Its Applications

[prokopetz]

Today's aesthetic: that specific era of video games right after doing 3D physics in real time became feasible but before game developers had learned when not to use it where sometimes you'd gently brush against the terrain slightly over some arbitrary velocity threshold and your character would immediately ragdoll like they'd been hit on the head.

[astrocatfizziks]

Quantum tunelling through a barrier

[quasi-normalcy]

Hey, so--we cooled your boyfriend down to a hundredth of a kelvin above absolute zero. Yeah, it was so cold that all of the chemical reactions in his body ceased. Sorry. We, uh, yeah, we used him as a dielectric material in a tiny qubit. And then we quantum-entangled him with another qubit, just to see if we could. Sorry. Yeah, anyway, we thawed him out after two weeks and apparently he's doing fine now. Didn't really teach us anything about how quantum processes work in biological systems, but it sure was, uh, cool. If you'll pardon the pun.

[er-cryptid]

alright nerds--

^tried to include as many as possible

[aromanrom]

Updates to projects

Introduction I didn���t post on this blog for a long time. Nevertheless, I didn’t stop the work on the projects. Most of them have improvements, some of them even serious additions. Some bugs are fixed and I even did some code cleanup to many of them. There are even a couple of newer projects on GitHub: QCSim and MachineLearning. This post is not about those, though, but about the changes and…

[ddejavvu]

pairing: Spencer Reid x reader

request: The BAU going to interview a witness in the hospital, only whenever Spencer is in the room, or speaks to reader in his soft voice, or touches them, their heart monitor starts beeping extremely loudly. Much to the amusement of the rest of the team. And to your sheer mortification. Spencer hypothesises maybe he looks like the unsub, poor guy has to get explained to him why he's wrong for once. And why they all keep sending him in to talk to you ;)

"Guys, I don't think I should go in there." Spencer's face is pinched in a concerned frown, and his teammates eye him with the same worry.

Derek claps a hand on Spencer's shoulder, "Why not, Reid? You're the only one she'll talk to."

"I think it's because she's afraid of me," Spencer admits, shoulders hunched uncomfortably inwards, "I think she's only talking because she's worried I'll hurt her, or something. I must look like the unsub."

"You think she's afraid of you?" Rossi questions, a paper cup of coffee in his hands that is entirely too empty for him to be having this conversation, "Reid, I don't think that's true."

Spencer presses onwards undeterred, shaking his head, sending his curls flying, "Every time I go in there I make her nervous. Her heart monitor starts going haywire, like she's having a flashback or something. I mean, one time I put my hand on her arm and the nurses flocked into the room because they thought the medication they'd given her was causing a seizure. I think I must remind her of the unsub somehow, and we can use that in the profile, but I don't want to keep tormenting her."

There's far too many seconds of prolonged, awkward silence. The team glances at Reid, at each other, at the floor, anything that will keep them from having to open their mouths. Eventually, Hotch steps into his role as leader, and moves through the cramped hallway towards Spencer's nervous, guilt-ridden trame.

"Reid, she's not nervous because you look like the unsub. She- squirms, and stutters, and you're the only one she'll talk to about what happened to her. If she were really negatively affected by your presence, she'd ask us not to send you in anymore. But she practically looks disappointed whenever anyone else tries talking to her. I don't think her heart rate increases because she's afraid of you."

Spencer's silent, his brows creased in thought, but perhaps even his genius brain can't parse this one out in a timely manner. Emily pipes up, "Reid, she's got a crush on you. And if that's what it takes to get this guy, then that's what we'll have to use. You're kind to her, and she's receptive to that. Now it doesn't matter the reason, but you can at least take solace in the fact that she's not afraid of you, okay? Not at all. That's why you have to go back in there, because you make her feel safe."

"No, I- I don't think that's what it is." Spencer's cheeks warm, pinkening beneath the hallway's fluorescent lighting, "I don't think she'd be able to form that sort of connection so soon after experiencing such a traumatic experience."

"That's exactly why she likes you," Derek insists, "You saved her. You swooped in and carried her to safety and now you're her knight in shining armor. And even if she won't feel this way forever, she feels it now, and you're the one she wants to talk to. You're the one that makes her feel safe. So go in there, and make her feel comfortable enough to help us catch this guy. Okay?"

Spencer's mouth tightens in a displeased frown for just a second, "I don't think you guys are right. I- I think it's something else. But I'll talk to her again."

"That's all we're asking." Hotch nods, pushing his shoulder gently towards the door of your room, "Now, go in there, and work your magic, Reid. We need more details."

Spencer turns the doorknob to your room with clammy hands, and finds you sleeping inside. He debates whether or not he should back out and let you rest, but for every minute he delays, their unsub walks free. He presses onwards, and the soft click of the door shutting behind him is enough to rouse your frayed nerves from sleep.

You jolt awake, eyes flying wide open and hands clenching the bedsheets like they're weapons you could use. Your eyes lock onto Spencer, and for a brief, terrifying moment, you stare at him like he'll attack you. But you drink in the curve of his nose, the puff of his lips, the messy ringlets of honey-colored hair that fall around his face, and your breathing evens out.

Your heart monitor, though, does not. Reid watches as your heartbeat stays frantic, and he moves slowly towards a chair by your bed in hopes of not spooking you any further.

"Hi, Dr. Reid." You murmur, your voice soft as you settle back against your pillow, "Is there any news on the investigation?"

"No, nothing new." Spencer admits, watching as you turn to face him. You angle your body entirely towards him, and you even scoot your head a centimeter closer on your pillow. Your face twists in displeasure at Spencer's admission, but you don't move away.

"Oh." You lay your cheek in your palm, "Did you want to talk to me more? I told you everything I know."

"I believe you." Spencer nods, "But l'm here to coach you through a memory exercise. You can stay laying down, but- take my hands?"

There's a slight blip in your heart rate, a missing beat where there should have been two. Then it kicks back up wilder than ever, and you take the hands Spencer's offering to you.

"Close your eyes," Spencer instructs, his own flitting towards your heart monitor where it beeps wildly.

"Think back to when he moved you. What sort of terrain was it? Did he go over any hills? Did it smell like animals?"

You squeeze Spencer's hands, nervous, and he squeezes yours back, "Just- remember, I'm here with you, l'll be here with you the whole time." You breathe deeply, and nestle closer to Spencer on the bed. Your hands are sweating in his own, which is a symptom Spencer knows all too well. You're leaning into him, begging for contact as you angle yourself towards him like a flower to the sun, and your heart rate steadily beeps at a mildly concerning level. Spencer keeps his voice steady as he leads you through the memory retrieval exercise, but nothing convinces him more that his team was correct than when it's over, and your eyes snap open, wildly, desperately searching for him.

"I'm here." Spencer hums comfortingly, and he knows that you're taking solace in him when you squeeze his hands, keeping him close instead of letting him go.

[andranikfakirian]

Project "CompMath.AstrophysicsODEs": Software Package

Finally, I got my hands on this project again. There is definitely a strong progress in the project at the moment: there is an alpha version of the software package. It is an ODE systems configurator, (m, k) - solver and visualizer combined with user-friendly interface. Unfortunately, currently only a version of solver with a constant timestep has been made, since the theory of Novikov methods is freely available only for such an implementation of the algorithm, as far as I know.

To create a solver with automatic timestep sampling, a couple of different algorithms are usually used. Based on the discrepancy in the solutions of the equations produced by these methods, it is decided wether to change the timestep in order to reduce the error by decreasing it, or, conversely, to lessen the total number of steps by increasing it. Among the methods described in the scientific literature with decent accuracy, there is only one calculated one. Thus, to manufacture more advanced solver, it is necessary to devise another algorithm and pair it with the first one.

And that's where the good news begins: after several hours of cumbersome "semi-automatic" calculations, another theoretical technique with all the necessary quotients has already been computed. Consequently, further implementation of the method with an automatic time step will be only a matter of technique.

In the meantime, you can admire the work of the software package with a "constant solver" on a very trivial stiff problem with an exponential analytic solution.

P.S.: The graphics below show the computed solution to a simple task (u(t)) and its relative error (uEps(t)) based on the deviation from the analytical solution. I ask you to pay attention to the fact that the error is really low (maximum about 0.0000025%) for a rather stiff problem (the value reaches 2.5·10^43 in one second).

[moonstonecanyon]

(06/07-09/2025.)

I might have a new babygirl,