> they’d spent a long time on solving this with algebra
I don't get it. I don't see why / how it would take any longer than a second or two to solve 'with algebra'. What does that even mean? You would just maybe write down the steps rather than doing them in your head. Is there any other way to solve the problem?
I'm pretty sure he means they did the problem by first figuring out the numbers a and b. That's the slow way. I can reveal the fast way if you want, but maybe you should think about it a bit more first! :)
I know the 'fast way'. Took me a second or two to get the answer, but it is so obvious that I cannot imagine anyone trying to solve this by calculating a and b first.
For novice students of algebra first learning to solve for values of variables, the idea of NOT solving for the values of the variables is a major step.
Quicker than an algebraic calculator, maybe, but very few people could get. faster with a slide rule than an ergonomic RPN calculator. like the HP 41 series. And I say that as an enthusiastic and experienced slide rule user, before I switched to a calculator.
One problem with a slide rule is that it only performs operations on normalized mantissas. You have to keep a parallel exponent calculation in your head, and that slows you down. Also, maintaining best precision slows you down.
When using a slide rule, keeping track of the number of digits to the left of the decimal point (DLDP) in the result is fairly simple if you know the basic rule:
For multiplication, the DLDP in the result is:
- the sum of the DLDPs of the multiplicands MINUS 1 if the multiplication is done with the slide sticking out to the right of the ruler's body (for example 2.0 x 3.0 = 6.0).
- the sum of the DLDPs of the multiplicands if the multiplication is done with the slide sticking out to the left of the ruler's body (for example 5.0 x 4.0 = 20.0).
There's a similar rule for division, but that's left as an exercise for the student.
> You have to keep a parallel exponent calculation in your head, and that slows you down
We were taught to estimate and use the rule to refine. I date back to the early electronic calculator era and we still had textbooks referencing slide rules etc.
"I want a dropping resistor for a plain old 1980s LED in a car" (back in ye old red LED 20 mA days) "Well experience indicates that will be far more than 500 ohms and somewhat less than 1K and IRL you're probably going to install a 680 and call it good" If you want an actual calculation for engineering purposes you calculate the ideal value under worst case conditions as about 585-ish ohms or whatever using the slide rule, purchasing LOLs at the idea of buying 0.1% precision resistors for mere LEDs, installs cheap 680 ohms and ships it. Maybe 680s if you want it bright to see in daylight or 820 if you want better odds to survive an alternator field winding dump or open battery (about the same thing). You can at least use the slide rule to verify everyone rounded in the "safer" direction to handle the worst case scenario.
I used an HP-41CV for many years. I needed the financial calcs module which I used in place of the dedicated HP financial calculator in grad school. Eventually gav out on me but was a good calculator for a long time.
I did keep a slide rule as a backup for exams in college when calculators were still LED but never really used one after a couple of years in high school.
The financial people I know all own 12Cs and they've been in continuous production since '81 although the innards are just a very boring ARM processor now.
They do what people want, the keyboard feel is infinitely smoother than tapping on a phone, etc.
I have an HP-41 app on my phone that the author gave to me when I was doing some product reviews early-on in the smartphone days. But definitely not the same as the physical HP calculator.
Yeah, the 12C was the standard in business school. But I needed a new calculator and the 41 with its various modules worked fine and was more general purpose.
Well said. I wrote an XSLT based application back in the early 2000s, and I always imagined the creators of XSLT as a bunch of slavering demented sadists. I hate XSLT with a passion and would take brainfuck over it any day.
Hearing the words Xalan, Xerces, FOP makes me break out in a cold sweat, 20 years later.
Ah, that brings back memories. I was using Intel iRMX on a commercial system in the mid 80s, and wanted to write a multitasking program on my IBM XT.
So I wrote a pre-emptive multitasking iRMX clone in C and a bit of assembler. Ended up using it to develop a mildly successful POS system running on a single PC with several VT100 terminals attached.
We had shared S100 8080 systems in our EE lab at university. 7 terminals per CPU. Worked just fine for editing programs. But when everyone started a (Pascal) compile run at the same time, things got plenty slow.
I’d note those competed with minicomputers, my high school had a PDP-8 circa 1981 when I was taking a few classes there while still in elementary school. The PDP-8 could support three terminals of interactive BASIC or could be brought up in a single user mode where you got more memory and could run bigger programs like the Crowther & Woods ADVENTURE. A bigger school has a PDP-11 with about 20 terminals. By 1985 or so my school got a VAX-11/730 which is basically like a modern computer.
That makes no sense whatsoever. We are not consuming rare earths; only moving them from one place to another.
Arguably, future generations would find it easier to mine them from former landfill sites, where they would be present in concentrated form, than from some distant mine in the middle of nowhere.
Will the NIMBYs of the future allow for rare earths processing in long defunct landfills that in the future are surrounded by residential development? These urban landfills even today really aren't far from civilization. In fact they have been enveloped by civilization in many cases.
I mean as it is you can't even recycle most things if they are the least bit soiled since it is not economically viable to implement a cleaning process. We are doing a whole lot of assumptions that our future members of our species will have solved a way to reliably get pure rare earths from a mixed up slop of everything in a landfill. Whatever they possibly figure out is going to probably be far more challenging than ore refining processes we use today.
It might be cheaper/easier to try and capture an asteroid than to refine a landfill.
Did they force you to gate check your bag, and then charged you a fee for it? That's what seems to be claimed here. I'm also pretty sure it'd be a violation of the carrier contract.
If it is within your allowence, but there "isnt enough space in the cabin" there will be no fee. If you turn up with 3 bags, bags that dont fit, or overweight bags they can and will charge you as a checked bag + a handling fee for the inconvenience.
You fly jets long enough, something like this happens.
> two people and four items of luggage plus a personal bag each
Well, there's you problem. I have traveled the world, including many trips of 6 weeks or more, with only a single. carry-on. Laundromats exist everywhere.
Snark aside, a bit of planning and organization w.r.t. packing pays off handsomely in terms of flexibility when traveling.
Spontaneous weekend trip to a remote island when carrying only a backpack - sure. Add two heavy suitcases, and it becomes an impossibility.
Please don't tell other people how they should live.
Personally I love travelling light (<10kg carry-on pack for 2 months last year to South America) but it isn't for everyone.
> Laundromats exist everywhere.
Only if you value your time at nearly $0. They are incredibly annoying when travelling - too often a 10 or 15 minute walk each way to one. Great for backpacking, but a complete waste of time if you only have a limited amount of time for your holiday.
Having just got back from a 8 week European vacation, with a wife+kid+me.
There's also the small issue of it being was 95F degrees outside at 75% humidity (southern France). This means 1 outfit isn't lasting more than a day (sometimes only 1/2 a day) before becoming unbearably stinky. x3 this means laundry needs to be done every other day or packing a ton of stuff.
I don't get it. I don't see why / how it would take any longer than a second or two to solve 'with algebra'. What does that even mean? You would just maybe write down the steps rather than doing them in your head. Is there any other way to solve the problem?