GRRRR part 2...

[Martin Brown]

On 03/06/2022 15:30, Phil Hobbs wrote:

Chris Jones wrote:
On 02/06/2022 23:33, jlarkin@highlandsniptechnology.com wrote:
There have been attempts to use computers to actually design
circuits, or at least to optimize values in a given topology. They
 tended to be ludicrous failures.

I used an optimizer for some chip designs, it was very very good for
 things like choosing the size of the transistors in flipflops for
best toggle frequency per supply current, and optimising a low pass
filter for best noise and in-band error-vector-magnitude and stop-band
rejection etc. all at the same time. It did way better than
I could have.

Sounds like a super useful tool.  I did something similar for optimizing
plasmonic nanoantennas 15 or so years ago, and like yours, it found good
solutions that weren\'t at all obvious.  So I\'m a fan of the general
approach.

Simulated annealing or simplex are pretty good for that sort of thing.
Then conjugate gradients once you get somewhere near an optimum.

You may never be sure you have the global optimum but it will probably
find a solution that is better than any human can in a reasonable time.

The trick was to write a script that runs the right simulations and
results in an expression (or several) that correctly describes how
well a circuit meets the goals. Once you\'ve done that, it can twiddle
the knobs much better than any human, and I don\'t mean because it
could do it faster and spam the simulations across a thousand CPUs
whilst you could look at only one at a time, it was also better in
that it could remember many sets of parameters that were good in
various ways, and combine them more efficiently than a human. It was
a company internal tool and they will surely have kept it that way.

Numerical optimization based on merit / penalty functions has been well
known for 200 years, since Gauss iirc.  That\'s a far cry from actual
computer-based design.

Even lenses, which you\'d think would be a natural application, have been
resistant to fully-automated design--it\'s all about finding a suitable
starting point.

Optical lens designs have been pretty much solved now at least in the
domains that I frequent. There could only be a handful of truly weird
configurations remaining that haven\'t been tried already.

The last interesting one in terms of being very different to orthodoxy
was Willstrop\'s three mirror telescope (no chromatic or sphereical
aberration, precise focus and very fast).

https://www.ast.cam.ac.uk/about/three-mirror.telescope

To the best of my knowledge no full scale one has ever been built.

I expect the odd novelty still lurks in the shadows. The search for
eyepieces with ever more wide angle views remains the Holy grail - they
are getting a bit ridiculous now with some offering 120 degree AFOV.

https://www.telescopehouse.com/Telescope-Accessories/EXPLORE-SCIENTIFIC-120-Ar-Eyepiece-9mm-2.html

I think that is the current record holder but I could be wrong on that.
Price and weight are both a bit on the high side (lots of glass in it).

There are various approaches that modify topologies, of which the best
known are genetic algorithms.

Modifying the topology is best done by humans. Optimising the components
against some library of available materials and shapes is now the domain
of sophisticated ray tracing programs. Zemax is probably the best known:

https://www.zemax.com/pages/try-opticstudio-for-free

Learning curve could best be described as STEEP...

--
Regards,
Martin Brown

 

[John Doe]

Samsung 980 Pro NVMe SSD 1TB PCIe 4.0 (Amazon)

Oom, baby.

The 2 TB version jumps to $270. But if money is no object, those two would
make an amazing primary and secondary drive combination. Primary being
smaller.

I\'m only using half of my 960 Pro (primary drive) and I already have the 980
original (secondary drive).









John Doe <always.look@message.header> wrote:

John Larkin wrote:

I\'ll need to get a new PC soon. People say that a screaming CPU and lots
of ram and solid-state C drive would really speed things up.

I have had NVMe drives for ages. Get good ones, like from Samsung. Spend
more than you used to spend on hard drives, it\'s well worth it. Primary
(and secondary) storage is not whizbang fun, but as IBM used to put it, it
affects \"throughput\" more than anything else. NVMe is what I have always
wanted.

If you use a secondary drive, the transfer rate between two premium NVMe
drives is OUTRAGEOUS. Transferring movies from your downloads folder to
the secondary drive is quick. Making backups of Windows is also quick.

 

[John Doe]

The 1 TB is $155. Great price.