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What sort of calculator do you use?
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This end up.
(Score: 3, Interesting) by DannyB on Wednesday December 11 2019, @06:11PM (10 children)
While I've tried and used the options listed ahead of CAS, my last purchased calculator was a TI-89. Fell in love with that. The CAS does for algebra what an ordinary calculator does for arithmetic. Want to factor this polynomial? Just punch it in and get the answer. All algebra results are simplified. Thus, when you do a "calculation" like 2+3, it is doing no algebra and merely "simplifying" the 2+3 to be the constant 5. In radians mode, punch in sin(π/3), it displays just the way I punched it in. The "pi" key didn't substitute in a number, it entered the symbol π. Then when I hit enter I find that sin(π/3) is √3/2, and is displayed that way.
I keep a TI-89 emulator on my phone, but now days I like wxMaxima on Linux. Fun stuff.
What doesn't kill me makes me weaker for next time.
(Score: 2) by The Mighty Buzzard on Wednesday December 11 2019, @07:45PM (7 children)
Yeah, I've poked buttons on all kinds myself but the most common kind I use in the very rare case that I can't do it in my head has #2 printed on the side. When even a pencil won't do it, I generally make a perl one-liner to do the heavy lifting.
My rights don't end where your fear begins.
(Score: 2) by DannyB on Wednesday December 11 2019, @08:05PM (6 children)
What if you have this equation and want to solve it for one of its variables.
2x+3y=29
I want to solve for x, type in: solve( 2x+3y=29, x )
and get back:
x = -(3y-29)/2
And type in: solve( 2x+3y=29, y )
and get back:
y = -(2x-29)/3
(I just did this on my TI-89 emulator)
Further, I would ask it to solve the equation for x again, but now tell it the value of y which I had just received, and I would get either an exact result for x, be it a number, a rational, something involving square roots, etc -- but NOT some long floating point decimal number. Although the exact expression I get back can be turned into an INEXACT floating point result with a keystroke.
Its as easy to manipulate expressions and equations as most calculators manipulate numbers.
I wouldn't expect Perl to do that. But I would expect some Lisps to do that with appropriate libraries loaded. Although as I mentioned, I've come to enjoy wxMaxima as a nice toy plaything.
What doesn't kill me makes me weaker for next time.
(Score: 2) by The Mighty Buzzard on Thursday December 12 2019, @12:21AM
You'd be amazed how never that tends to happen even in the life of a generic computer programmer. Life generally doesn't give you many problems with the exact same way to get to the answer, so formulas more complex than checkbook balancing (I know, I'm old) aren't a common, useful thing. I think the last time I used a calculator was when I was designing the amp stages for an FM transmitter I built and needed resistor and capacitor values. That was around the time NCommander was asking for alpha testers on IRC from a bunch of folks who had a penchant for saying Fuck Beta.
My rights don't end where your fear begins.
(Score: 2) by All Your Lawn Are Belong To Us on Thursday December 12 2019, @03:54PM (3 children)
You have a point and I don't want to make it sound like you don't. I could use my HP to do basically what you did... plus you can just sub in one of the variables and get the numeric result a lot easier...
But the two manipulations you showed are something I can just do in my head.
Subtract 3y, divide by 2 and you get x = (29-3y)/2 and y = (29-2x)/3. No need to extract the -1 if you follow the order of operators.
No, you can't ask me to do that with more complex equations and the calculator can. :)
This sig for rent.
(Score: 2) by DannyB on Thursday December 12 2019, @04:07PM (2 children)
Mostly it is fun. I find these CAS calculators to be really fun toys. Something unthinkable in the early days of the first calculators, even scientific calculators. I remember an algebra teacher saying something about how calculators don't factor polynomials, or something to that effect. :-) Because calculators were purely numeric at the time.
As a pre-algebra teenager, I played with my calculator a lot, and began to discover some basic algebra relations without realizing it. In algebra class, I suddenly remembered, I figured this out by trial and error, over a number of test cases, that, for example: a^2 * b^2 = (a*b)^2. But what I had done was not proof that it worked for all values of a and b.
Similarly, I enjoy playing with CAS calculators. I can learn things that I wouldn't learn by actually doing this playing on paper and pencil. Mostly it's just fun.
What doesn't kill me makes me weaker for next time.
(Score: 2) by All Your Lawn Are Belong To Us on Thursday December 12 2019, @07:29PM (1 child)
Sure is! I played for hours with my 28C, getting it to do stuff like output a random string of beep tones and then trying to correct that the beep function altered it's length along with the pitch so all the beeps would sound for the same length of time. Played around with the calculus functions even though I didn't know anything about calculus then. Then I created a program in it to play a game of HighLow with me via the stack.
If I remember correctly the 28C also had a unit that was undefined ("unit") and/or let one define one's own units in terms of other units. Made it so much easier when one was dealing with the unusual, although it did have some limitations. I've missed that ever since when trying to deal with unit conversions for units that weren't defined. I have to go off and find a unit that is completely unrelated to what I'm calculating (Joules usually work) and sub that in.
This sig for rent.
(Score: 3, Interesting) by DannyB on Thursday December 12 2019, @08:55PM
IIRC, Joules could be expressed in terms of the fundamental units they picked. Several of the units would have non-zero exponents.
I used the example of velocity. That would have an exponent of 1 for the Length unit, and an exponent of -1 for the time exponent. That gives length per time.
One fun thing I did, since it was possible to display arbitrary pixel content onto the display, was to display a Calvin & Hobbes icon, which I pilfered from a classic Mac icon someone else had already drawn in 32x32 B&W. I did have to rotate it, turn it into the proper hex code, etc.
What doesn't kill me makes me weaker for next time.
(Score: 2) by barbara hudson on Thursday December 19 2019, @01:41AM
I just pick a guesstimate that's reasonable, see if it fits, and keep on until I get the solution. Gives me practice in spotting stuff that doesn't make any sense at all. Like when someone used the wrong unit of measurement for a Mars probe. You should be able to eyeball the answer to tell that it's nowhere in the ballpark.
I knew one guy who had a calculator that couldn't add properly - the final result was always only around 10% of what it should have been. He'd bring it to sales, and have the seller use his calculator to add up the total bill.
And they would accept it because they couldn't come up with a rough estimate in their heads.
Gerry was a crafty SOB.
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(Score: 3, Interesting) by richtopia on Sunday December 15 2019, @01:37AM (1 child)
The TI-89 was one of the best purchases I ever made. The TI-83 I had through high school and undergrad was good, but if I had purchased the 89 earlier I could have done better on some of my exams.
Today, my TI-83 sits in a drawer of my cube. Its primary purpose is adding taxes for expense reports, but even for that it is much preferred over the Windows calculator. The TI-89 is somewhere in my house.
(Score: 1, Interesting) by Anonymous Coward on Sunday December 15 2019, @03:39AM
I have a TI-89 Plus Titanium but, IIRC, of the very few exams that let me use a graphing or programmable calculator none (or very few) of them allowed me to use a TI-89. They can be useful for homework though. I also have a TI-84 Plus Silver edition.