## Does anyone else create formulae on the spot?

For the discussion of math. Duh.

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King Author
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### Does anyone else create formulae on the spot?

Whenever I see a table or list or whatever of numbers compared to something, I think up a formula to represent the progression. For example, I was just watching Good Eats and they showed times to cook lobster for, based on weight.

Lobster Cooking Time by Weight
1 lb. - 10 mins
1 & 1/4 lb. - 12 mins
1 & 1/2 lb. - 14 mins
1 & 3/4 lb. - 16 mins
2 lb. - 18 mins

Immediately, I thought to myself, "two minutes plus two minutes-per-quarter-pound." I do things like this all the time. I don't intend to, it just sort of happens. Anyone else do the same?
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Syrin
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### Re: Does anyone else create formulae on the spot?

I just acknowledge that there is a formula - I leave the rest to the constructivists.

Mike_Bson
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### Re: Does anyone else create formulae on the spot?

I do that, too, OP. I cannot help it.

Xanthir
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### Re: Does anyone else create formulae on the spot?

Yup, me too. It helps when interpolating or extrapolating recipes.
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achan1058
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### Re: Does anyone else create formulae on the spot?

The problem is, there are infinitely many formuli which will give the specified result. Try Lagrange Interpolation.

Torn Apart By Dingos
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### Re: Does anyone else create formulae on the spot?

I don't. I consider linear formulopodes too trivial and non-linear ones too difficult.

Dason
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### Re: Does anyone else create formulae on the spot?

achan1058 wrote:The problem is, there are infinitely many formuli which will give the specified result. Try Lagrange Interpolation.

Yes but typically there is an obvious candidate. If you can model something linearly then that's probably what you should be using.
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TiglathPileser3
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### Re: Does anyone else create formulae on the spot?

Torn Apart By Dingos wrote:I don't. I consider linear formulopodes too trivial and non-linear ones too difficult.

Actually, quadratics (and lower degree polynomials) are pretty easy, as are exponential/logarithmic curves. I guess logistic or something like that might be hard.

gmalivuk
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### Re: Does anyone else create formulae on the spot?

Dason wrote:
achan1058 wrote:The problem is, there are infinitely many formuli which will give the specified result. Try Lagrange Interpolation.
Yes but typically there is an obvious candidate.
Yeah, this is a pretty unoriginal and useless response to any discussion about finding the pattern:

We bloody well *know* that there are infinitely many patterns consistent with the finite data we've been given. But luckily our brains are not just blank general-purpose computing machines, and so we can also bring in other knowledge about the world to conclude what the most reasonable solution is, even though it's not the only possible solution.

Also, achan, if you're going to try and be a pedant, you might try spelling formulae correctly...
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duckshirt
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### Re: Does anyone else create formulae on the spot?

King Author wrote:Immediately, I thought to myself, "two minutes plus two minutes-per-quarter-pound." I do things like this all the time. I don't intend to, it just sort of happens. Anyone else do the same?

So if I have no lobster, I still have to cook an empty plate for two minutes? (Does anyone else debug formulae on the spot?)
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TusksRUs
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### Re: Does anyone else create formulae on the spot?

I guess the formula is only defined for positive nonzero amount of lobster

squareroot
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### Re: Does anyone else create formulae on the spot?

I try to reason-out the order of the function (for small and large x), and then I try to find a formula that fits reasonably well. I realize that for a spoonful of lobster, I won't be cooking it for just over 2 minutes. So I try to make something up that doesn't deviate too far from the "correct" values, but seems reasonable for limits too.
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gmalivuk
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### Re: Does anyone else create formulae on the spot?

Why? How long *would* you cook a spoonful of lobster?
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King Author
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### Re: Does anyone else create formulae on the spot?

Xanthir wrote:Yup, me too. It helps when interpolating or extrapolating recipes.

It's also cool when nobody around you remembers any of their fifth-grade algebra and you seem like some sorta wizard by being able to re-tool recipes on the fly.

achan1058 wrote:The problem is, there are infinitely many formuli which will give the specified result. Try Lagrange Interpolation.

Problem...or awesomeness?

TiglathPileser3 wrote:
Torn Apart By Dingos wrote:I don't. I consider linear formulopodes too trivial and non-linear ones too difficult.

Actually, quadratics (and lower degree polynomials) are pretty easy, as are exponential/logarithmic curves. I guess logistic or something like that might be hard.

I like quadratics, but they're too difficult to make up on the spot. All the formulae I spontaneously generate are simplistic eighth-grade stuff.

duckshirt wrote:
King Author wrote:Immediately, I thought to myself, "two minutes plus two minutes-per-quarter-pound." I do things like this all the time. I don't intend to, it just sort of happens. Anyone else do the same?

So if I have no lobster, I still have to cook an empty plate for two minutes? (Does anyone else debug formulae on the spot?)

XD

TusksRUs wrote:I guess the formula is only defined for positive nonzero amount of lobster ;)

I don't think the phrase "a non-zero amount of lobster" has ever been uttered or written before, lol.

gmalivuk wrote:Why? How long *would* you cook a spoonful of lobster?

That's a trick question -- you wouldn't cook a spoonful of lobster, you'd serve it as sashimi.
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nash1429
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### Re: Does anyone else create formulae on the spot?

King Author wrote:It's also cool when nobody around you remembers any of their fifth-grade algebra and you seem like some sorta wizard by being able to re-tool recipes on the fly.

I believe by "cool" you mean "disgusting." Seriously, some of the math that people get amazed at-being able to calculate the tip in my head is *not* magic.

Jermoe
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### Re: Does anyone else create formulae on the spot?

King Author wrote:
Xanthir wrote:Yup, me too. It helps when interpolating or extrapolating recipes.

It's also cool when nobody around you remembers any of their fifth-grade algebra and you seem like some sorta wizard by being able to re-tool recipes on the fly.

None of my friends care if I can think up a formula on the fly to model some real life thing, all they care about is when I make an arithmetic error in my head so they can laugh at me....Remember: Mental Arithmetic is the true measure of one's mathematical skill, with solving real world problems coming in somewhere under finger painting.

If only people would let me write stuff down more often....

t1mm01994
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### Re: Does anyone else create formulae on the spot?

Quadratics and linears here.. And, occasionally, an exponential, but just when it fits the bill really well, and you end up with something like 2^(x-1). I can recognize those ...
But yeah, pretty much for anything, formulae!

Mike_Bson
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### Re: Does anyone else create formulae on the spot?

t1mm01994 wrote:Quadratics and linears here.. And, occasionally, an exponential, but just when it fits the bill really well, and you end up with something like 2^(x-1). I can recognize those ...
But yeah, pretty much for anything, formulae!

Inverse variation is pretty easy, too.

Eastwinn
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### Re: Does anyone else create formulae on the spot?

Torn Apart By Dingos wrote:I don't. I consider linear formulopodes too trivial and non-linear ones too difficult.

This.

Typically I avoid math when watching a cooking show. Cooking shows are for looking at pretty food and cleavage. The latter is not the case for Good Eats.
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King Author
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### Re: Does anyone else create formulae on the spot?

nash1429 wrote:
King Author wrote:It's also cool when nobody around you remembers any of their fifth-grade algebra and you seem like some sorta wizard by being able to re-tool recipes on the fly.

I believe by "cool" you mean "disgusting." Seriously, some of the math that people get amazed at-being able to calculate the tip in my head is *not* magic.

Heh, it is a sad reflection on the state of mathematical understanding in this country. There's this one hiimdaisy comic (which I can't find after twenty minutes of thumbing through her Livejournal) on Apollo Justice where Miles is displaying all his "magical powers" as the audience oohs and aahs at his amazing insight, which concludes with, "A rare gun was used to kill the victim. The defendant was found in posession of such a rare gun. Therefore, he used the gun to kill the victim." Oooh! Aaaah! (Magical Power #3: Basic Logic).

Eastwinn wrote:
Torn Apart By Dingos wrote:I don't. I consider linear formulopodes too trivial and non-linear ones too difficult.

This.

Typically I avoid math when watching a cooking show. Cooking shows are for looking at pretty food and cleavage. The latter is not the case for Good Eats.

*fanning himself*
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Eastwinn
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### Re: Does anyone else create formulae on the spot?

King Author wrote:
nash1429 wrote:
King Author wrote:It's also cool when nobody around you remembers any of their fifth-grade algebra and you seem like some sorta wizard by being able to re-tool recipes on the fly.

I believe by "cool" you mean "disgusting." Seriously, some of the math that people get amazed at-being able to calculate the tip in my head is *not* magic.

Heh, it is a sad reflection on the state of mathematical understanding in this country. There's this one hiimdaisy comic (which I can't find after twenty minutes of thumbing through her Livejournal) on Apollo Justice where Miles is displaying all his "magical powers" as the audience oohs and aahs at his amazing insight, which concludes with, "A rare gun was used to kill the victim. The defendant was found in posession of such a rare gun. Therefore, he used the gun to kill the victim." Oooh! Aaaah! (Magical Power #3: Basic Logic).

Sometimes I get amazed faces when I perform calculations in my head quickly. I find that mental math skills often come when someone has a strong intuition for algebra that transcends the symbols and the academics. For example, my brother, presented with a simple equation, would not be able to solve for a particular variable. However, if you were to give him a practical situation that required the same actions, he would solve it intuitively. These are the people, I think, who are naturally good at mental math.

I tried to explain to my mother a "trick" for multiplying by fives. It's a simple trick that my brother and I were never taught, but knew and used intuitively. If you're multiplying an even number by five, split that even number in half, and then add a zero on the end. If it's an odd number, subtract one from the number to get an even number, split that even number in half, and then add a five on the end. Super simple, but it was magic to her. She tries to brag about my brother and I for this any chance she gets.

I have my hypotheses (is that what the plural is?) about these things.. but they're unsupported besides my experience and guesswork so far, which is not science makes.
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Xanthir
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### Re: Does anyone else create formulae on the spot?

Eastwinn wrote:I tried to explain to my mother a "trick" for multiplying by fives. It's a simple trick that my brother and I were never taught, but knew and used intuitively. If you're multiplying an even number by five, split that even number in half, and then add a zero on the end. If it's an odd number, subtract one from the number to get an even number, split that even number in half, and then add a five on the end. Super simple, but it was magic to her. She tries to brag about my brother and I for this any chance she gets.

Obviously that works for dividing numbers by five as well. It's just /2*10, or *2/10.
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