Hacker News: kurlberg

New comment by kurlberg in "Canonical/Ubuntu have been under DDoS"

kurlberg — Fri, 01 May 2026 15:12:06 +0000

I had the same impulse (or at least copy.fail inducing many to upgrade at the same time.) However, it might be a "pro-Iran hacktivist group" according to

https://www.theregister.com/2026/05/01/canonical_confirms_ub...

"Canonical says its web infrastructure is under attack after a pro-Iran hacktivist group instructed its members to target the open source giant."

Perhaps more to do with extortion rather than activism. (I have no idea how accurate theregister is on this story.)

New comment by kurlberg in "The math that explains why bell curves are everywhere"

kurlberg — Thu, 19 Mar 2026 14:21:19 +0000

Convolution alone does not smooth. Eg consider a random variable supported on the pts 0 and 1 (delta masses at 2 pts.) No matter how many convolutions you do, you still have support on integers - not smooth at all. You need appropriate rescaling for a gaussian.

Also, convolving a distribution with itself is NOT a linear operation, hence cannot be described by a matrix multiplication with a fixed matrix.

New comment by kurlberg in "Ask HN: Books to learn 6502 ASM and the Apple II"

kurlberg — Tue, 27 Jan 2026 14:31:40 +0000

Read it as a young teenager, can recommend.

New comment by kurlberg in "DIY NAS: 2026 Edition"

kurlberg — Thu, 27 Nov 2025 09:15:59 +0000

This has been discussed on HN some times before. User xornot looked at the zfs source code and debunked "faulty ram corrupts more and more on scrub", for more details see https://news.ycombinator.com/item?id=14207520

New comment by kurlberg in "The Microsoft SoftCard for the Apple II: Getting two processors to share memory"

kurlberg — Wed, 05 Nov 2025 12:33:56 +0000

I don't think this is entirely due to Wozniak. Early "home" computer systems were based on connecting cards to a bus (eg the S-100 bus), eg. with one card supporting the CPU, another RAM, a third for disk drive, video card etc, etc. The cards where then memory mapped, presumably you controlled the memory mapping by setting jumpers. (I guess you're saying that Apple II managed this automatically?) Of course the full story might be a bit more complicated: 6502 and 6800 used memory mapped I/O, whereas 8080 (and Z80?) had certain I/O pins coming out of the CPU.

New comment by kurlberg in "The Unknotting Number Is Not Additive"

kurlberg — Thu, 09 Oct 2025 09:18:02 +0000

Fun historical fact: knot theory got a big boost when lord Kelvin (yeah, that one) proposed understanding atoms by thinking of them as "knotted vortices in the ether".

New comment by kurlberg in "Busy beaver hunters reach numbers that overwhelm ordinary math"

kurlberg — Mon, 25 Aug 2025 06:29:03 +0000

If you have a child who likes math I highly recommend "Really Big Numbers" by Richard Schwarz. Tons of nice illustrations on how to "take bigger and bigger steps".

"Infinity is farther away than you thought."

New comment by kurlberg in "FreeBSD for hi-fi audio: real-time processing, equalizer, MPD and FFmpeg"

kurlberg — Thu, 06 Feb 2025 14:26:00 +0000

I recently got into making some sort of budget hifi setup, and found audiosciencereview.com quite helpful - a good amount of reviewed gadgets with focus on measurements. Ended up with kali lp-6v2 speakers and a SMSL SU-1 dac. Please don't tell me I screwed up. :-)

New comment by kurlberg in "OpenWrt 24.10.0 – First Stable Release"

kurlberg — Thu, 06 Feb 2025 09:57:13 +0000

I have used merlin for quite a while, mostly happy (except for some security holes...) However, once asus drops support for older devices (e.g. rt-ac68u and rt-ac86u), merlin might also drop it. For now rt-ac68u is dropped by merlin, but ac86u is fine for now (at least until the end of the year.)

Upshot: if you care about very long term support, openwrt is nice.

New comment by kurlberg in "OpenWrt 24.10.0 – First Stable Release"

kurlberg — Thu, 06 Feb 2025 09:52:44 +0000

Based on reddit [1] and other some other recommendations I got an asus ax4200 and put openwrt on it. I'm fairly happy, but some people have run into connection dropping (possibly due to ISP power saving resulting in link dropping down to 10 mbs, and something then goes wrong.) With forum help [2] I found a workaround: either turn off auto negotiation (works) or using a lan port as a wan port (have not tried).

https://www.reddit.com/r/openwrt/comments/1cr1lvp/is_the_asu...

https://github.com/openwrt/openwrt/issues/14192#issuecomment...

New comment by kurlberg in "Convolutions, Fast Fourier Transform and polynomials (2022)"

kurlberg — Mon, 01 Jul 2024 14:55:54 +0000

PS: if you're interested in multiplying "ludicrously large numbers", Harvey and van der Hoeven had a nice breakthrough and got multiplication down to "FFT speed" (n*log(n)), see

https://hal.science/hal-02070778v2/document

A pop-sci description can be found at

https://theconversation.com/weve-found-a-quicker-way-to-mult...

New comment by kurlberg in "Convolutions, Fast Fourier Transform and polynomials (2022)"

kurlberg — Mon, 01 Jul 2024 14:46:16 +0000

There is a nice picture of the "best" for different ranges of sizes of numbers to be multiplied at

http://gmplib.org/devel/log.i7.1024.png

More context and explanation can be found at: http://gmplib.org/devel/

BTW, I like Bernstein's survey of different multiplication algorithms at

https://cr.yp.to/papers/m3.pdf

(there is a unifying theme about using ring isomorphisms to explain many of the "standard" routines.)

New comment by kurlberg in "Making AI better at math tutoring"

kurlberg — Thu, 27 Jun 2024 16:19:03 +0000

Check out "Diamond Age" by Neal Stephenson.

New comment by kurlberg in "How to generate uniformly random points on n-spheres and in n-balls"

kurlberg — Wed, 06 Mar 2024 07:16:31 +0000

It's very inefficient, both on terms of runtime and in terms wasted entropy.

New comment by kurlberg in "Please Use ZFS with ECC Memory (2014)"

kurlberg — Sat, 06 Aug 2022 19:31:26 +0000

This has been discussed on HN some times before. User xornot looked at the zfs source code and debunked it, for more details see

https://news.ycombinator.com/item?id=14207520

New comment by kurlberg in "Signed integers are asymmetrical"

kurlberg — Mon, 25 Oct 2021 10:30:41 +0000

Yes, it has uses. E.g., see Kahan's "Branch Cuts for Complex Elementary Functions, or Much Ado About Nothing's Sign Bit", copy available at

https://people.freebsd.org/~das/kahan86branch.pdf

(he gives an example regarding complex branch cuts and fluid dynamics applications.)

New comment by kurlberg in "ZFS fans, rejoice – RAIDz expansion will be a thing soon"

kurlberg — Fri, 18 Jun 2021 22:22:29 +0000

Years ago I saw it at:

https://www.truenas.com/community/threads/ecc-vs-non-ecc-ram...

(the gist of the scary story is that faulty ram while scrubbing might kill "everything".) However, in the end ECC appears to NOT be so important, e.g., see

https://news.ycombinator.com/item?id=23687895

New comment by kurlberg in "Digital Needle: Ripping vinyl records with a scanner (2013)"

kurlberg — Tue, 27 Apr 2021 11:50:20 +0000

There is an extremely nice "Digital show and tell" video by Monty at

https://xiph.org/video/vid2.shtml

(part 1 at https://xiph.org/video/vid1.shtml is also very well worth watching.)

New comment by kurlberg in "Analyzing the Design of Unusual Japanese Butter Tableware"

kurlberg — Sun, 18 Oct 2020 16:52:22 +0000

I lived in the states for a while and missed Bregott. "Land o Lakes butter with canola oil" is a pretty good substitute.

New comment by kurlberg in "A modular, extensible DIY NAS"

kurlberg — Mon, 05 Oct 2020 21:14:15 +0000

According to

https://www.servethehome.com/hpe-proliant-microserver-gen10-...

the 10+ seems to run freenas fine.