Calculators and numerical differentiation

11032020, 06:09 PM
Post: #7




RE: Calculators and numerical differentiation
(11012020 05:39 PM)Albert Chan Wrote: How did you deduce there is hidden CAS under nonCAS Nspire ? I may have made a leap in my logic, but the fact that examples such as x or 1/x at x=0 or at x=0.0001 produce the correct answer in the nonCAS Nspire while these are incorrect on the 84+ lead me to believe that the nonCAS model must be doing something CASlike under the hood. I had never come across a counterexample. It also made sense to me the it would be very easy to share the same code as the NspireCAS for such calculations. You prompted me to look in the Nspire manual which gives some insight. Quote:nDerivative() (The Npsire has a centralDiff() function as well that behaves like the 84+.) The part starting with "Note: " is not in the Nspire CAS manual. The Nspire CAS gives the correct answer for this example. When I first saw the above example, I thought that I must have been wrong about the numeric model having an internal CAS since the numeric model does not give the correct answer while the CAS model does. However, now that I'm reading it again, I'm thinking that I may have been right after all. The fact that it says "the subexpression (x^2+x)^(1/3) is undefined at x=0" means that the calculator must be breaking the expression down into subexpressions and evaluating their derivatives (consistent with the product rule) which means that it must have some CAS capabilities rather than just evaluating the whole expression numerically. So my current thinking is that the Nspire must have at least some CAS capabilities under the hood, but not to the extent as the Nspire CAS. Thoughts? 

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Messages In This Thread 
Calculators and numerical differentiation  robve  10302020, 09:57 PM
RE: Calculators and numerical differentiation  Paul Dale  10302020, 11:41 PM
RE: Calculators and numerical differentiation  Albert Chan  10312020, 01:20 AM
RE: Calculators and numerical differentiation  Wes Loewer  11012020, 05:39 AM
RE: Calculators and numerical differentiation  Albert Chan  11012020, 05:39 PM
RE: Calculators and numerical differentiation  Albert Chan  11012020, 11:43 PM
RE: Calculators and numerical differentiation  Wes Loewer  11032020 06:09 PM
RE: Calculators and numerical differentiation  Albert Chan  11032020, 10:14 PM
RE: Calculators and numerical differentiation  Wes Loewer  11042020, 04:14 PM
RE: Calculators and numerical differentiation  CMarangon  11032020, 06:55 PM
RE: Calculators and numerical differentiation  Wes Loewer  11042020, 04:04 PM

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