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Topic: improvement on sin(x) = −0.4176x^2 +1.3122x -
0.0504 ;; we need semicircle sine, not the fakery of sinusoi
d sine

Replies: 15   Last Post: Feb 25, 2017 3:31 AM

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 plutonium.archimedes@gmail.com Posts: 18,323 Registered: 3/31/08
probably need to go to a 3rd power polynomial
Posted: Feb 20, 2017 1:42 AM

Alright, at bare minimum I need to get this table:

x y
0 0
.5 .86
1 1
1.5 .86
2 0

Now I can come reasonably close by .1 or less, but if more than .1, the game is off

So far, the best two equations for sine and cosine are these two

-.4x^2 + 1.6x + .09

-.6x^2 - .3x +1

Troubles: the first gives 0 as .09, then gives .8 which is good, but gives 1.3 when I need 1. The second gives 1 at 0, good, then .7 when I need .86, then .1 when I need 0 which is acceptable. So unless I can mend the two to fit better, then I must go to a 3rd power polynomial.

AP