I do not use, and have never used, a slide rule. My grandfather was an aeronautical engineering / materials scientist for McDonnell Aircraft, and did a lot of foundational work on heat shields for early space flight (or so I am told). He was eventually named a McDonnell Douglas Fellow, back when there were fewer than 15 Fellows - the company, at the time, took out a full-page ad in Aerospace Magazine announcing it.
I have his slide rule, that he used for ages. It's a mystery in a box to me - I have not the foggiest clue how it is used - but I cherish it.
> I have not the foggiest clue how it is used - but I cherish it.
It's easier and more straightforward than you might expect. I encourage you to learn to use his slide rule, in large part because you might find it fun, but also to honor your grandfather's legacy.
I agree. In fact you should make a (YouTube?) video showing the slide rule and how to use it and your grandfather’s history to preserve this bit of history for your family and family’s future descendants.
A key idea is that addition for logs is equivalent to multiplication. To multiply two numbers you line them up on a log scale and then read out the sum, which is equivalent to the product. There is much more they can do but that was one aha moment when my dad showed me his.
I've never used a slide rule but recently developed an interest in them (and also in nomograms [1])
My fascination stems from a belief: that slide rule usage helps users develop a certain intuition for numbers whereas the calculator doesn't. To illustrate, suppose someone tries to multiply 123 and 987 with a calculator but incorrectly punches in 123 and 187. My hypothesis is they'll look at the result but won't suspect any problem. The equivalent operation on a slide rule requires fewer physical actions and hence, is less error prone.
Nomograms are cool. They're little charts that let you compute a function physically, e.g. by lining up a ruler. A nomogram isn't a picture of a function: it is the function. If you're clever, you can make a nomogram that encodes complicated nonlinear mappings or even complex-valued relationships on a 2D plane.
Occasionally nomograms are just better too: because they're continuous and analog, they can naturally express things digital logic people can do only awkwardly, just like Rust people can only awkward approximate things natural in Verilog (e.g. truly parallel CAM search).
Nomograms are basically the tabletop gaming of math. Like a good tabletop game, a good nomogram requires a special kind of cleverness. Sure, coding something like Factorio is also hard: but it runs on a CPU. Something as rich and complex as Power Grid and High Frontier? Running on cardboard? Whole other level.
I recall one tabletop two-player game that featured a single-player mode in which you played against an "AI" that you ran by hand by moving cardboard pieces around on a game-provided template under pseudocode-ish rules from the game manual. It's hard enough to code a decent game AI with all the resources of a CPU at your disposal. It's an OOM harder to do it when you're limited to physically-realized lookup tables, a literal handful of registers, and a scant few clock cycles of logic per turn.
Coming full circle, some of these tabletop game "AI"s incorporate nomograms to help them fit their logic within the constraints.
Example of a cool nomogram: https://en.wikipedia.org/wiki/Smith_chart. Smith charts let you compute complex (pun intended) relationships in RF signal processing with just a compass and straightedge.
Also: part of the fun in making nomograms is that there's no general procedure you can follow to make a good one, just like there's no general compiler from computer game to tabletop game. They're art: specifically, one of those forms of art that, like architecture, has to meet functional requirements while tickling our aesthetic sense. It's kind of funny how when you optimize this kind of art for aesthetics under their functional constraints, you end up supercharging the functional part by side effect somehow.
With a slide rule you always have to estimate the expected answer in your head before you begin any calculation. So you develop a feel for how quantities scale with multiplication.
With a slide rule you can only multiply the significant digits, not the magnitudes -- which you have to do in your head. So you do exactly the same thing with the slide rule to multiply 123 and 987, 1.23 and 9.87, and 1,230 and 9,870. In all three cases, you get exactly the same answer: 121 or maybe just 120 (you only get 3 digits of precision at best). You still have to multiply the powers of ten in your head, to get the answers 121,000, 12.1, and 12,100,000.
I am just old enough to belong to the last generation of slide rule users. I used them in high school and college, then scientific calculators came along.
You don't have to multiply the powers of ten in your head. In your examples, the slider of the slide rule must be moved to the left of the body of the rule. This means the number of digits left of the decimal point in the answer is the sum of the number of digits left of the decimal point in the two multiplicands.
If the slider had been to the right of the body, the number of digits left of the decimal point in the answer is the sum of the number of digits left of the decimal point in the two multiplicands MINUS 1.
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Yes. I don't recall doing this, though. Maybe because in scientific and engineering calculations we often worked in scientific notation so 'digits to the left of the decimal point' wasn't meaningful - we had to keep track of the exponents.
It's not the number of actions, it's because the slide rule is analog and physical. The smaller numbers are to the left, the larger to the right, and you have to slide the rule to the first number, then the hairline cursor to the second number. There's no way you could mix up a large number like 987 with a small number like 187.
Exactly. Using a slide rule shows how some complex operations in one domain can be made much easier in another.
One you understand slide rules and logarithms, it is easier to understand convolutions in the FFT (frequency) domain...
Almost like programming in APL, where you can solve a problem by expanding it in extra dimensions and getting the answer by re-compacting the complex object using a different view.
I had a similar experience! My grandfather worked at a paper company for years and years as a chemical engineer. He was a hot head, but lightened up as I got older. We started to connect well later in life because I was the only other "engineering type" in my family.
He gave me his slide rule probably a year or so before he passed away. I've got it sitting on my desk and always makes me think of him. Like you, I've got no idea how to use it (even though he tried to explain it to me), so maybe the other comments here can fill in the gaps for me :)
My grandfather was a computational meteorologist for the US Air Force who passed when I was a kid. I inherited both his slide rule and his laptop (a 486dx with a math coprocessor!) It felt cool being the only kid at the school with a laptop, but the slide rule languished in a box under my bed until I got it out and figured out how to work it in college. I wish I'd figured it out sooner because it gave a more visceral understanding of the mathematical relationships that I'd been lacking before. Granted, the slide rule has sat mostly idle since then, but it was definitely worth it. I'd encourage you to give it a go.
Me too! My grandfather worked in construction among other things and gave me his slide rule some years before he died. He showed me how to use it but I don't remember (though what he gave me came with instructions).
trump would love a government shutdown, as he has proven. I really doubt shutting down the govt would change any situation when trump is legislating by executive order, and mostly a shutdown would hurt Americans. You're trying to simplify something that isn't simple at all, and blame the Democrats for not doing what an armchair expert wants.
It's not just about what Trump wants. Most Republicans in Congress would like to get reelected.
In the comment above you suggested there's nothing congressional Democrats can do. That is incorrect. Any time the Republicans don't have unanimity, and any time they need sixty votes in the Senate, the Democrats have leverage. They need the guts, and/or the understanding of basic game theory, to use it.
Calling me an "armchair expert" and waving your hands about how things are complicated is not a counterargument.
> I already mentioned the budget. If Republicans want to pass any actual tax cuts, that's another opportunity.
Not really, given the budget reconciliation process and its applicabilty to that: bypasses the filibuster entirely and only a simple majority is needed with a 20-hour capped debate time ij each house.
> Senate Minority Leader Charles E. Schumer (D-New York) said Thursday that he planned to support the Republicans’ funding bill; he needed at least seven other Democrats to overcome a filibuster and set the vote up for final passage. Nine others who caucus with Democrats joined him and nearly all Republicans voted to advance the measure....The 62-38 vote came after days of turmoil among Senate Democrats who were split on either working with President Donald Trump and Republicans to pass a continuing resolution that includes $13 billion in cuts to nondefense spending or allowing the government to shut down.
You're crying that Democrats won't do anything, when they do not have the power to stop this. You're in need of some education about how the government works.
I could not disagree with these points more. I cannot speak to other faiths, but having been raised as a Christian (and having read the Bible in its entirety at one point), this form of Christian apologism neatly steps over the logical incongruities and moral failings fundamental to Christianity.
It's the absence of belief in a deity - and therefore the recognition that the starting conditions of our lives was random chance, out of our control - that provides the foundation that all humans are equal and of equal value. That after 14 billion years of my atoms circling the universe I sprung forth, child of middle-class but reasonably well-educated parents in the United States, and not the child of struggling farmers in Australia, or drug addicts in Eastern Europe, was complete chance. To me this means that I am of no more importance than people born to those situations, irrespective of what they eventually managed to accomplish.
It's the absence of belief in a deity - and therefore the realization that life is finite, precious, non-transferable, and fair in so far as much is the product of chance - that means we should prefer human life over sentient robots. The consciousness of a one-day sentient robot will likely be transferrable, and therefore durable mostly indefinitely. Mine consciousness is, as of yet, not.
It's the absence of belief in a deity that neatly solves the problem of evil in the world. And so on, and so forth.
I'm happy for people to be comforted by religion, as they hurtle through a probabilistic universe, trying to fill the time between their birth and their death with meaning and enjoyment. When we die, it's unlikely that even a single lifetime later people then alive will even know or think about how we ever existed. So do what you must to be comfortable now. It'll all be over soon.
> It's the absence of belief in a deity - and therefore the recognition that the starting conditions of our lives was random chance, out of our control - that provides the foundation that all humans are equal and of equal value.
This is absolutely false if by "equal value" you mean anything other than "of no more value than any other product of randomness". But I doubt you believe that you and the drug addict in Eastern Europe are equally worthless (and equivalent to the return value of `head -c 100 /dev/urandom`). In fact, you say "the realization that life is ... precious". "Precious" to who, precisely?
> It's the absence of belief in a deity that neatly solves the problem of evil in the world
This is the same failing as above - it solves the problem of evil by removing evil as a category. There is only the actions of random chance, which cannot be evil. But you clearly still believe in evil. Where comes the good that evil opposes?
Bravo, very good questions in the socratic method.
Christianity has so deeply penetrated our society that we don't even notice it's precepts anymore. It's like the air we breathe. It's so prevalent, it's become invisible to our eyes.
1. > It's the absence of belief in a deity... that provides the foundation that all humans are equal and of equal value.
Historically, this is not true. A couple Greco-Roman philosophers entertained the idea, and surely other cultures here and there did too, but until Christianity, societies in the West believed might makes right. Which makes sense, because this is how the natural world works. Evolution is, at it's core, survival of the fittest. What lasts is what is most fit to reproduce.
Humans being of equal value as conceived in the West is derived straight from Christian philosophy. The Gospels, Paul, St Augustine, Erasmus, Descartes, Leibniz, Locke, etc. This is a widely accepted point, and don't expect to argue this point further, since you can research it extensively.
Perhaps for you, personally, an atheistic belief provides this foundation, and that's perfectly fine, but this is not how it played out.
2. > It's the absence of belief in a deity - and therefore the realization that life is finite, precious, non-transferable, and fair in so far as much is the product of chance - that means we should prefer human life over sentient robots. The consciousness of a one-day sentient robot will likely be transferrable, and therefore durable mostly indefinitely. Mine consciousness is, as of yet, not.
This is without any solid foundation. Why does the transferability of human conciousness matter in terms of its sanctity? You can't poop out what I just pooped, but you don't consider it sacred? And this mentality is restricted purely by technology. Who's to say we couldn't transfer consciousness in the future?
It is also entirely non-falsifiable to say that we came about purely by chance. This athiestic view is actually just as fantastical as a Christian view. You might as well say you believe in Fortuna, rather than God, since the two views are equally dogmatic.
3. > It's the absence of belief in a deity that neatly solves the problem of evil in the world.
How? How do you determine what is right and wrong? If it's purely subjective, then there actually isn't right and wrong. They don't exist.
Christianity answers the problem of evil easily in the book of Job. You can't possibly understand everything God does, therefore you gotta make-do with what you're taught, and if something seems out of place in the world, it's God doing his divine plan. You can't understand it all.
4. > When we die, it's unlikely that even a single lifetime later people then alive will even know or think about how we ever existed. So do what you must to be comfortable now. It'll all be over soon.
This is another dogmatic view that is just as non-falsifiable as any view about the Christian afterlife. To say "nothing happens after we die" is just as rigid as to say "we go to heaven after we die". At least one is frank that it's dogma, and like you say, more comforting and useful in terms of providing moral guidance.
Am on a Dutch train right now and there is a distinct lack of roll, Dutch or otherwise.
That said, I wonder where the term Dutch Roll comes from. Perhaps the oscillation is reminiscent of the motion of a ship rocking side to side. The Dutch were a major sea power.
Sounds like you didn't have receive side scaling enabled; by default flows are queued to core 0 to prevent reordering. If you enable RSS, your flows will be hashed to core-specific queues.
It's inaccurate to describe traffic processing as single-threaded in the kernel.
I have his slide rule, that he used for ages. It's a mystery in a box to me - I have not the foggiest clue how it is used - but I cherish it.