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

blogs.scientificamerican.com

21–30 of 144 posts

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

#21

"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.

The log tables let you work without slide rules, which were themselves horribly expensive not too terribly long ago in the grand scheme of things. But yes, this was all about practical calculation, not mathematics for its own sake, that needed to be carried out quickly by people who wouldn't have handy access to machines that keep the dirty arithmetic details (and potential for error) hidden from the operator, whether that's your ship's navigator or the machinist with nothing but a sine bar and gauge blocks setting up a precision operation, and if you needed precision using a four-figure table book, the only way you were going to get it was if the derived operations were in the tables.

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

#22
post #5

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

Did you read the article?

Many of the commenters appear not to have, which is disappointing. I thought the article did a nice job of explaining what they are, and why they're no longer relevant.

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

#23

Earlier quoted context omitted.

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 wi…

I don't agree at all. This happens all the time. For example, electrical engineering has f, ω, and s, all only differing by basic factors of 2π or i.

As far as I can tell, the main reason this gets done is to give commonly recurring quantities single symbols, to reduce errors in lengthy calculations. When those recurring quantities are meaningfully different, in ways that help prime one's intuition, that's all the more reason to do it.

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

#25
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 always bugged me that secant is 1/cosine, cosecant is 1/sine, and cotangent is 1/tangent. Like what does co- mean?

Trigonometry never really clicked for me. I can remember the formulas and such, but I never really understood what they meant. It was an exercise in remembering but never knowing.

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

#26
post #25
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 always bugged me that secant is 1/cosine, cosecant is 1/sine, and cotangent is 1/tangent. Like what does co- mean? Trigonometry never really clicked for me. I can remember the formulas and such, but I never really understood what they meant. It was an exercise in remembering but never knowing.

The prefix 'co-' stands for complementary. Two complementary angles add up to 90°. The cosine of a angle is therefore the sine of its complementary angle, etc.

For the secant and tangent, it originates from the geometry of the unit circle. The first image in the article explains it well.

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

#27

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/

A few sentences in.

> "Sanskirt for 'chord'

Sanskrit, you mean?

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

#28

Earlier quoted context omitted.

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 wi…

I don't agree at all. This happens all the time. For example, electrical engineering has f , ω , and s , all only differing by basic factors of 2 π or i . As far as I can tell, the main reason this gets done is to give commonly recurring quantities single symbols, to reduce errors in lengthy calculations. When those recurring quantities are meaningfully different, in ways that help prime one's intuition, that's all t…

You also save clock cycles by avoiding the extra calculation each time you compute 2pi or whatever by defining TWO_PI once. So it was lot more common in Fortran and C programming days.

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

#29
Here's one I came across on Facebook the other day. I had no recollection of it from school, but it's pretty neat and it appeared in someone's cheat sheet of standard trig formulas with double angles and all that familiar stuff.

https://en.wikipedia.org/wiki/Mollweide%27s_formula?wprov=sf...

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

#30

Earlier quoted context omitted.

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 wi…

I don't agree at all. This happens all the time. For example, electrical engineering has f , ω , and s , all only differing by basic factors of 2 π or i . As far as I can tell, the main reason this gets done is to give commonly recurring quantities single symbols, to reduce errors in lengthy calculations. When those recurring quantities are meaningfully different, in ways that help prime one's intuition, that's all t…

As an electrical engineer you'll typical use f, ω, and s, in different contexts and you'll learn each of those contexts separately.

f: consumer electronics ω: circuits s: frequency response

Having multiples of terms for each is definitely a hindrance to education. It makes switching between each use a mental headache.

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