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theodorethomas

77 karma · joined August 9, 2021

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theodorethomas··on Celebrating 70 Years of Fortran
You know, I have read this a lot. But the Programmer's Reference Manual, dated October 15, 1956 clearly has it as Fᴏʀᴛʀᴀɴ, which used "small caps", so I am not so sure anymore.

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theodorethomas··on Celebrating 70 Years of Fortran
There is one under-appreciated aspect of Fortran.

Here is something that started as a specification of the input format of one particular program-tool. That input format was then cloned and mutated by dozens of me-too program-tools. Eventually that format was able to support an interpretation as a language with its own language-like abstractions. That is astonishing and I think was not on the radar of computing machinery people in the 50s.

theodorethomas··on Celebrating 70 Years of Fortran
many such cases
theodorethomas··on Icy Moons Are Ocean Worlds
I object to this mis-use of the word "ocean". If I can't sail there then it's not an ocean. Luckily, Titan still has an ocean. But all the others have iceans.
theodorethomas··on How bicycle coaster brakes work (2018)
Yes, this is how I used the "handbrake" function to "park" on a steep uphill.
theodorethomas··on Turns are Better than Radians (2022)
The Fortran 2023 Standard introduces new intrinsics:

"The intrinsic functions ACOSPI, ASINPI, ATANPI, ATAN2PI, COSPI, SINPI, and TANPI are trigonometric functions in which angles are specified in halfrevolutions (that is, as multiples of π)."

theodorethomas··on LEDs’ potential to save our night skies
I wondered if a city-wide synchronised Pulse-Width-Modulation of LED lights could allow astrophotography (or even naked-eye astronomy) to be possible again, with a filter synchronised to the off-cycle.
theodorethomas··on Ada, its design, and the language that built the languages
Reading the Steelman document is like reading a shopping list of everything that's gone into modern Fortran.
theodorethomas··on All elementary functions from a single binary operator
I wonder how this combines with Richardson's Theorem.
theodorethomas··on Intel 486 CPU announced April 10, 1989
Except the 486 had hardware floating point, essential for technical work.
theodorethomas··on Intel 486 CPU announced April 10, 1989
The 486 and https://www.delorie.com/djgpp/history.html changed everything.

Suddenly, it was possible to imagine running advanced software on a PC, and not have to spend 25,000 USD on a workstation.

theodorethomas··on Lunar Flyby
One consequence of that is that the Earth, as seen from the nearside of the Moon's surface, just hangs there, never moving, apart from a small wobble.
theodorethomas··on Why so many control rooms were seafoam green (2025)
Apollo Command Module interior colour is similar, and gorgeous.
theodorethomas··on What came after the 486?
I remember a 120MHz Pentium Linux box arriving at a cottage in Crete, where, with the aid of a 56k USRobotics modem, we (my wife and I) worked remotely in 1995-6. She had a Mac SE/30 for her tourist guidebook work. She later upgraded to a 6100 PowerMac "pizza-box", various iMacs, G3/G4/G5, whereas I saved a quad-200MHz PentiumPro monster (Compaq Professional Workstation 8000, tricked up to 3GB RAM) from the skip. I regret taking that to the recycling centre many years later.
theodorethomas··on Nobody gets promoted for simplicity
There are two ways of constructing software: one way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult.

— C. A. R. Hoare

theodorethomas··on What to Do When the Trisector Comes (1983) [pdf]
The sheer amount of dedication is awe-inspiring. In the 80s, at Imperial College, London, Theoretical Physics Group, we came across some correspondence intended for one of the professors, I think. This person had evidently "translated" his native Spanish into English, laboriously, via some dictionary we thought. We spent many tea breaks puzzling over phrases such as

"Is well-knew the refran: of the said to made it has a good road."

theodorethomas··on Fortran Outsmarted Our Billion-Dollar AI Chips
"The language assumes contiguous memory, column-major order, and no hidden aliasing between arrays."

One out of three ain't bad.

"Column-major order", that's the one. That just says that there is an implied order of elements of an array. This enables efficient mapping of an array of the language definition to storage with a linear address space. It does not require storage to be organised in any particular way.

"Contiguous memory". Not really, the language definition does not even use the word "memory". The language is carefully defined so that you can implement it efficiently on a linear address space in the presence of caches (no accident that IBM machines in the 80s were pushing caches while CRAY was pushing vector processors). The term "contiguous" in the language definition just means a collection whose parts are not separated by other data objects.

"no hidden aliasing between arrays". This is a crude mis-statement of the actual rule of argument association across subroutine/function caller-callee boundary. The rule takes pages to describe fully. A language that still has EQUIVALENCE statement (although marked obsolete) cannot be said to disallow aliasing. It is still quite hard to find a compiler that will reliably diagnose inadvertent aliasing at runtime. The actual rule in Fortran says something like "thou shall not cause any effect on (dummy name) A through a reference to some other name, unless (some-clause-x or y or z)".

theodorethomas··on John Carmack on mutable variables
Do as much as you can in a spreadsheet, then start a new spreadsheet.
theodorethomas··on The Prehistory of Computing, Part II
Part I managed to miss the Antikythera Mechanism.
theodorethomas··on Introducing tmux-rs
It is not suited to cases where the machine state is experienced by the user at all times (games, hardware-control, real-time transactions). It is very suited to cases where the machine is expected to act like a SSBN, disappearing from view until a large floating-point calculation is ready.
theodorethomas··on What does “Undecidable” mean, anyway
Can someone explain to me why although we've known that classical physics is not a correct description of the hardware of the universe for at least 100 years now, we are still hooked on 90-year-old Turing Machines which cannot physically exist (they violate quantum mechanics) and whose theoretical limitations are, consequently, irrelevant.
theodorethomas··on Vatican Observatory
Before smartphones we had https://www.cambridge.org/turnleft
theodorethomas··on Ways to generate SSA
FORTRAN (IBM, 1956) introduced the "Computed GOTO".

SSA (IBM, 1988) introduced the "Computed COMEFROM".

theodorethomas··on It's time to abandon the cargo cult metaphor
At my age, I assume that everything that "everybody knows" has a large dollop of fiction pasted around it.

"Byzantine generals", anyone?

theodorethomas··on The origin of the cargo cult metaphor
Ken, I love your work on the Apollo hardware.

But here, you don't present any argument that your recommended course of action will have a desirable outcome, or any outcome at all.

Which, ironically, fits like a glove.

Fine, I get it, the term has been over-used and has consequently become meaningless. Orwell noted the over-use of "fascist", in 1944! Feel free not to use it. But surely you are not expecting some kind of outcome?!

theodorethomas··on 20 Years of "Not Even Wrong"
> why some of the very best theoretical physicists, who were entirely free to work on whatever they wanted, continued working on string theory

Historically, it is not unusual for intellectual wrong turns to persist for decades or centuries. On the flip side, brilliant insights can also be abandoned too early.

The problem here is that data has dried up and cannot guide us. Some future tech will open up new data and then progress will resume. Without data, physics becomes theology.

__________________________________________ Feynman's talk "Seeking New Laws" excerpt: "But the age that we live in is the age in which we are discovering the fundamental laws of nature. And that day will never come again. I don’t mean we’re finished. I mean, we’re right in the process of making such discoveries. It’s very exciting and marvelous, but this excitement will have to go.

Of course, in the future there will be other interests. There will be interests on the connection of one level of phenomena to another, phenomena in biology and so on, all kinds of things. Or if you’re talking about explorations, exploring planets and other things. But there will not still be the same thing as we’re doing now. It will be just different interests.

Another thing that will happen is that if all is known– ultimately, if it turns out all is known, it gets very dull– the biggest philosophy and the careful attention to all these things that I’ve been talking about will have gradually disappeared. The philosophers, who are always on the outside, making stupid remarks, will be able to close in. Because we can’t push them away by saying, well, if you were right, you’d be able to guess all the rest of the laws. Because when they’re all there, they’ll have an explanation for it.

For instance, there are always explanations as to why the world is three dimensional. Well, there’s only one world. And it’s hard to tell if that explanation is right or not. So if everything were known, there will be some explanation about why those are the right laws.

But that explanation will be in a frame that we can’t criticize by arguing that that type of reasoning will not permit us to go further. So there will be a degeneration of ideas, just like the degeneration that great explorers feel occurs when tourists begin moving in on their territory."

theodorethomas··on Fortran 2023
https://wg5-fortran.org/N2201-N2250/N2212.pdf is John Reid's complete document.
theodorethomas··on Things Every Hacker Once Knew (2017)
Mid 1980s, trying to connect from one London University computer (at Imperial, a CDC Cyber?) to another (at Queen Mary?), to try some symbolic algebra package that was only available on a Unix minicomputer: spent a good 2 hours just finding the right terminal settings and configuration settings for all the intervening software. Left me feeling I would rather code what I could on an 8-bit 2Mhz 64K machine.
theodorethomas··on Chomsky explains why nobody is a moral relativist
I suspect not. Children are exposed to far less text than LLMs. LLMs are parlour tricks that teach us nothing about how humans do it.
theodorethomas··on Is Fortran easier to optimize than C for heavy calculations?
The point is, it shouldn't.

https://news.ycombinator.com/item?id=30022022 How ISO C became unusable for operating systems development

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