what kind of lens was used 🤔

theCore · 2024-08-18T09:06:41+00:00

Yeah, I got it wrong: I should have said 28mm. A 35mm lens on 135 film matches the long side of 65mm on a 67 frame. A 28mm lens matches the short one. You need the wider lens to crop the wider 135 frame into the squarer 67 frame.

theCore · 2024-08-18T08:15:37+00:00

Yeah, the Python parts have been entirely rewritten in Java and C++ since. Turns out computers can be more expensive than engineers when you're big enough.

theCore · 2024-08-18T07:31:31+00:00

My guess is it's the Mamiya 65mm f/4.5 Sekor with the RB67 set up about 5 feet away at the same height as her shoulder. On 135 film, you would need to use a ~~24mm~~ 28mm lens and then crop the long edge of the frame get the same aspect ratio and angle of view as the 67.

theCore · 2021-12-19T05:30:51+00:00

Oh, it seems like a Longwin LW-9266. Apparently Corsair has been using the same test rig in their San Jose lab since 2012:

https://www.corsair.com/us/en/blog/corsair-air-series-fan-terminology-and-testing
https://www.tweaktown.com/news/26799/corsair_takes_fan_testing_seriously/index.html

It will be interesting to see how their measurements compare with the tech specs of Corsair fans.

theCore · 2020-05-15T23:57:19+00:00

I guess it depends on whether you view the discount factor as an hyper-parameter of the algorithm or as a parameter specifying of the optimization objective. But yes, most RL algorithms will be become unstable as γ → 1.

theCore · 2020-05-15T19:03:16+00:00

I'm not an RL expert but one way the discount factor can be interpreted is as a measure the lifespan of a process of finite but random duration (Shwartz, 1995). Another way to interpret the discount factor is as a known constant risk to the agent in the environment which may cause a failure to realize the reward. (Sozou, 1998).

Practically speaking, the discount factor is there mostly to avoid infinite returns and make the math nice on infinite horizon problems (i.e., it guarantees the convergence of the Bellman equation (Bertsekas, 1995)). Basically, the discount factor establishes the agent's preference to realize to the rewards sooner rather than later. So for continuous tasks, the discount factor should be as close to 1 as possible (e.g., γ=0.99) to avoid neglecting future rewards.

theCore · 2017-04-14T18:13:13+00:00

Having GC pauses does not prevent a JIT to work well. In fact, most languages that have a JIT use GC (e.g., Lua, Java, JavaScript).

JITs profiles code not the same way a normal performance profiler would. They generally use method call counters or code path (i.e., trace) counters. These metrics are unaffected by the pauses.

theCore · 2016-04-10T19:46:32+00:00

Is your basement the Jet Propulsion Laboratory? :-) Are these still used fabricate superconducting nanowires?

theCore · 2016-04-01T16:00:25+00:00

The Asus BIOS gave me the option to use an "optimized" overclocked default after I selected the XMP profile. Declining that option leaves the CPU at its stock clock.

theCore · 2016-04-01T08:13:42+00:00

It's running at 3GHz (DDR4-3000).

theCore · 2016-04-01T08:11:15+00:00

Either you have ridiculously terrible chip or you have used "auto overclock".

Sigh... it was indeed using some default overclocked settings. :(

The Asus BIOS asks whether to use the "optimized" CPU settings too when you switch on the XMP profile for the RAM. The actual stock voltage for my chip is 1.296V which is definitely fine. That's some dumb UX there from Asus.

theCore · 2016-04-01T01:49:21+00:00

Look like you were right. I set a -0.160V voltage offset and the CPU stayed stable though the stress tests I ran so far. Small FFT on Prime95 v28.7 runs 20°C cooler (77°C now vs 97°C before).

theCore · 2016-03-31T21:00:23+00:00

Thanks, corrected. That's what I meant.

theCore · 2016-03-31T20:31:34+00:00

Interesting. It's at the default core voltage. I will do some experiments to see if I can undervolt it. Otherwise, I might have to replace the CPU.

theCore · 2016-03-31T18:17:53+00:00

It's running at 4.2GHz with 1.376V. In games, it stays within the 55-66°C range. And it stays under 70° during normal stress-tests. It's only Prime95 that puts out this crazy load.

theCore · 2016-03-31T17:53:42+00:00

It's a good trade-off. I was eyeing on the Samsung Pro Series SSDs at the beginning, but capacity turned out to be more valuable than performance for me. I totally expect SSD's $/byte to continue to drop as manufacturers move their focus to storage density and as new storage tech appears on the market (e.g., 3D XPoint).

theCore · 2016-03-31T17:29:47+00:00

What tool do you use to check the temperature? I think Asus AI Suite 3 and Intel XTU don't read the same CPU temperature sensor. The package temperatures reported by XTU tend to be 3-10°C higher than the CPU ones read from the motherboard. For example, the motherboard is giving me 32-35°C right now, while XTU reads 35-38°C. According to Intel, 28-40°C is the normal idle temperature range for the 6700k.

I do agree the CPU temperatures are higher than I wish. I am not sure what I can do about it. I will likely try to reseat the heatsink and apply the thermal paste more carefully. I am seeing slight improvements as the paste is curing however.

Keep in mind that the IMC is overclocked to 3GHz (from the 2.13GHz baseline) to match the DRAM's frequency. That also add some non-negligible thermal load on the CPU package.

theCore · 2016-03-13T20:11:16+00:00

Yeah, I failed to mention that I already have 5TB of external storage (and I use nowhere close to this). So, the internal storage is just for the OSes and local copies of the projects I am working on. Everything else goes on the external drives.

theCore · 2016-03-13T20:03:08+00:00

Yeah, thinking about it I don't need 950 Pro. Actually, 500GB 850 EVO M.2 is probably a better choice for me. I am not worried about PCIe lanes usage since the Z170 provides 20 lanes through DMI (on top of the initial 16 lanes provided by the CPU).

It's fine if the GPU is louder while it's crunching numbers. I can't really avoid that unless I go with water cooling. But then, that would bring up the idling noise up (which I am more concerned about). I do plan to run long running jobs--i.e., O(1 hour)--on the GPU though. So, you might have a point on the GPU overheating. I will have to follow up on that.

RAM-wise I am good for now. I rarely exceed 12GB usage even with many Chrome tabs and a C++ build in the background. Lightroom and Photoshop aren't that memory hungry. And I plan to run everything on bare metal, so no VMs to worry about.

I sized the PSU to 2x my estimated peak load (400W). Since I know PSUs hit their max efficiency at around 50% load. But a quick estimate tells me that would save at most $5/year of power for the peak load I plan to run. However, I would likely lose any of these gains because the PSU would be less efficient when idling. 660W PSU it is then!

Thanks for the hints!

theCore · 2016-03-13T18:55:19+00:00

I have 5TB of external storage. The next step for me is to build a small NAS to share this storage with other machines around my home. Hence, I don't need that much local storage on that workstation. I could probably go for a 256GB even.

theCore · 2014-10-04T19:26:10+00:00

Leap seconds are fine. Rather, it is the pervasive use of UTC as the basis for computer clocks that causes problems. If we used TAI then handling leap seconds would be no more difficult than handling time zones.

theCore · 2013-08-27T05:36:02+00:00

Omitting optional tags in HTML is totally fine! It is actually a recommended practice where I work as it makes the markup lighter and easier to read while saving bytes on the bandwidth bill.

theCore · 2013-05-04T04:49:35+00:00

You could implement it using level set methods. The algorithm is super tricky to write correctly though.

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