- #1
SprucerMoose
- 62
- 0
Gday,
I'm encountering a rounding error on my Ti-nspire CAS and was wondering if this approximation is acceptable.
For the function f(x) = (x^2 +1)sin(x), I obtained (by hand, confirmed with CAS) a derivitive of f'(x) = 2xsinx + (x^2 + 1)cos(x).
Calculating the minima of f(x) with the CAS yields x=-20.5173. However, if i plug this value into f'(x) manually, a result of f'(-20.5173) = -0.002071 is obtained. This is the biggest rounding error I have encountered and I was wondering what's going on. Strangly though, if I ask the CAS to do d/dx (f(-20.5173)) the result is 0. I am assuming that this x value is not a true minima, as plugging it directly into the raw derivitive should be most accurate? Any help would be appreciated.
I'm encountering a rounding error on my Ti-nspire CAS and was wondering if this approximation is acceptable.
For the function f(x) = (x^2 +1)sin(x), I obtained (by hand, confirmed with CAS) a derivitive of f'(x) = 2xsinx + (x^2 + 1)cos(x).
Calculating the minima of f(x) with the CAS yields x=-20.5173. However, if i plug this value into f'(x) manually, a result of f'(-20.5173) = -0.002071 is obtained. This is the biggest rounding error I have encountered and I was wondering what's going on. Strangly though, if I ask the CAS to do d/dx (f(-20.5173)) the result is 0. I am assuming that this x value is not a true minima, as plugging it directly into the raw derivitive should be most accurate? Any help would be appreciated.