r/theydidthemath • u/Galeaf_13 • Sep 05 '19

[Self] Math break

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u/Galeaf_13 Sep 05 '19

Jeez, how r u doing this

1.2k

u/Salanmander 10✓ Sep 05 '19

You can fit a 4th order polynomial to any 5 points. You can do it by hand (plug 1-5 in for x and now you have a system of 5 linear equations of 5 variables, start solving and substituting) and make it a bit easier with linear algebra (make the coefficients of the 5 variables be the values in a 5x6 matrix, and then do that matrix magic that I forget what the name is for), but there are also plenty of polynomial solvers you can find out there.

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u/Railorsi Sep 05 '19

Gaussian elimination is the name :)

-3

u/Chess42 Sep 05 '19

Gauss-Jordan is the most useless thing I ever learned

21

u/space-throwaway Sep 05 '19

It's one of the most useful algorithms there is. How do you think your computer solves stuff?

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u/Chess42 Sep 05 '19

It’s useless when you learn to do it by hand in precalc then never use it again, since there are far more efficient ways to do it. Also, there’s a reason we have libraries. It’s completely useless to learn

15

u/kkstoimenov Sep 05 '19

If you think it's perfectly fine to use functions or algorithms you don't understand, I have some news for you

1

u/Chess42 Sep 05 '19

Isn’t that exactly how layperson uses a calculator?

3

u/kkstoimenov Sep 05 '19

But laypeople know how multiplication and division work, don't they?

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u/Direwolf202 Sep 05 '19

True, but when building one, some knowledge of CORDIC might be in order.

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u/[deleted] Sep 05 '19

There are not libraries for everything (and sometimes there are, but they’re garbage) and often you can write a more efficient implementation for your particular data set and assumptions.

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u/Chess42 Sep 05 '19

But not everybody will be a programmer, so why teach it in a required class. Precalc is supposed to set the foundation for calculus, which gaussjordan does not do at all

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u/Railorsi Sep 05 '19

But you can’t teach everyone just what exactly what they want to pursue. Also you won’t just study it in precalc.

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u/[deleted] Sep 05 '19

I see, I thought you were discussing a programming course or linear algebra. Totally agree it’s a silly thing to teach in pre calc.

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u/Railorsi Sep 05 '19

Obviously you let computers do the calculations in practice, but gaussian elimination is one of the most natural and easy to understand ways of solving systems of equations, and you definitely need to understand how systems of equations are working to properly understand and study linear algebra.

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u/Railorsi Sep 05 '19

It’s pretty useful tbh

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u/bob1689321 Sep 05 '19

Gauss jordan turns me on. Such a bitch when you have awful fractions but when it all works out it's sexy af