Obsolete trig functions and why we don't use them anymore (2013) • Hacker News Board

Re: Obsolete trig functions and why we don't use them anymore (2013)

#11

Post by klodolph » Thu, Dec 03, 2020, 4:54 AM UTC

kortex wrote: post #6

Vers- is just from versus "opposite/against". But versine isn't opposite of sine, if anything it's opposing cosine. I too am curious this how this naming convention arose.

It is opposite the sine, it is at a right angle. Look at the circle diagram: the "sinus rectus" goes vertically and the "sinus versus" goes horizontally.

Re: Obsolete trig functions and why we don't use them anymore (2013)

#12

Post by framecowbird » Thu, Dec 03, 2020, 5:02 AM UTC

anonytrary wrote: post #3

"goobledegook = e + 5.6. Wow you didn't know about goobledegook? Let me teach you about this revolutionary concept." I majored in mathematics and can say I've never heard of versine and have probably used it many times without knowing. I don't think everything needs a name.

versine clearly needed a name once when it was in common usage. As in, "Hey Greg, can you help me? I can't find this computation in these tables. --- Oh, try the versine".

Re: Obsolete trig functions and why we don't use them anymore (2013)

#13

Post by [deleted] » Thu, Dec 03, 2020, 5:03 AM UTC

[deleted]

Re: Obsolete trig functions and why we don't use them anymore (2013)

#14

Post by framecowbird » Thu, Dec 03, 2020, 5:03 AM UTC

_vmyf wrote: post #5

bruh this is just adding constants to regular functions ((((top secret))))

Did you read the article?

Re: Obsolete trig functions and why we don't use them anymore (2013)

#15

Post by extremelearning » Thu, Dec 03, 2020, 5:09 AM UTC

For those interested in this topic, I wrote a similar blog post on the geometric interpretation of the various trig functions, which also includes some similar diagrams for the hyperbolic trig functions: sinh, cosh, tanh, sech, etc.

http://extremelearning.com.au/trigonometry-visualised/

Re: Obsolete trig functions and why we don't use them anymore (2013)

#16

Post by pacaro » Thu, Dec 03, 2020, 5:09 AM UTC

I'm not that old, but I learned the haversine formula in a marine navigation class I took through (boy) scouts. Our instructor was a retired merchant navy officer who was somewhat upset that the curriculum didn't include it, and deemed that we should know it.

My A-level (≈ AP) maths teacher was mildly amused that I knew it and digressed about log tables. We were (I believe) the last cohort to be issued log-tables, but given the choice in examinations between log-tables, slide-rule, or calculator, we all made the same choice.

Re: Obsolete trig functions and why we don't use them anymore (2013)

#17

Post by anonytrary » Thu, Dec 03, 2020, 5:10 AM UTC

Waterluvian wrote: post #10

anonytrary wrote: post #3

"goobledegook = e + 5.6. Wow you didn't know about goobledegook? Let me teach you about this revolutionary concept." I majored in mathematics and can say I've never heard of versine and have probably used it many times without knowing. I don't think everything needs a name.

It kind of helps a non Mathie like me doing trig. But I'll ask fof one better: I would love an application that lets me plug in what I have (coords and angles), what I want, and for it to show me how to get it.

Does it? No one does this:

  var STRAWBERRY_PI = 1 + Math.PI;

For example, no one doing math will use τ (2𝛑) and 𝛑 simultaneously. Choose one or the other, otherwise you are increasing the number of symbols someone has to learn to understand your math. Naming everything is overwhelming. Mathematics is about similarities, not differences. If the transformation is trivial, then don't bother creating a new symbol. It will just confuse you more.

Re: Obsolete trig functions and why we don't use them anymore (2013)

#18

Post by pacaro » Thu, Dec 03, 2020, 5:13 AM UTC

pacaro wrote: post #16

I'm not that old, but I learned the haversine formula in a marine navigation class I took through (boy) scouts. Our instructor was a retired merchant navy officer who was somewhat upset that the curriculum didn't include it, and deemed that we should know it. My A-level (≈ AP) maths teacher was mildly amused that I knew it and digressed about log tables. We were (I believe) the last cohort to be issued log-tables, bu…

I'm also mildly amused that the author failed to mention the hyperbolic functions, of which there is one for each of the regular circular trig functions

Re: Obsolete trig functions and why we don't use them anymore (2013)

#19

Post by netsec_burn » Thu, Dec 03, 2020, 5:28 AM UTC

An even greater secret: sinh, cosh, tanh. Don't tell anyone. This message will automatically self destruct in 5.. 4.. 3..

Re: Obsolete trig functions and why we don't use them anymore (2013)

#20

Post by todd8 » Thu, Dec 03, 2020, 5:37 AM UTC

desertrider12 wrote: post #9

anonytrary wrote: post #3

"goobledegook = e + 5.6. Wow you didn't know about goobledegook? Let me teach you about this revolutionary concept." I majored in mathematics and can say I've never heard of versine and have probably used it many times without knowing. I don't think everything needs a name.

I think the point of these was for when they read low-precision values out of a printed table and then multiplied them using slide rules. Even though the article doesn't say it, I can't think of any other practical reason to multiply by adding logarithms.

Generally, slide rules were only good for rough calculations (3 significant digits if you were lucky), but they did contain multiple scales providing multiplication, division, exponential, log10, ln, roots, sin, cos, tan, and hyperbolic trig functions. Notably one couldn’t do addition or subtraction with a slide rule; we used pencils for that.

When more precision was needed, I and my fellow engineers would break out our copies of CRC’s reference tables. The better log tables allowed calculations to 5 or 6 significant digits. Using these were not unusual and all of us learned to use them in high school (before 1970 at least).