Re: numerical derivatives

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Re: numerical derivatives

And using the nDer(expression,variable,value) function try this...

In the graph Menu enter the following functions...

y1=2x^3+3x^2+6x+5
y2=nDer(y1,x,x)
y3=6x^2+6x+6
y4=abs(y3-y2) + 1

Set the ZOOM Mode to normal.. and Only plot the y4 Function.  If you get a
straight line at Y=1 then your derivative "Listed in Equation Y3" is correct.
  Formula Y4 says take the absolute value of the nDER function minus the value
of the actual Algebraic derivative and then add 1 and plot the answer.
        This will give you a "STRAIGHT" line at Y=1 if the functions Y2 and Y3 are
numerically equivalent. It's a great test of your derivatives..


Mr.Data
TI 8x, 9x, and Z-80 Nut case...
-----Original Message-----
From: Open discussion of TI Graphing Calculators
[mailto:CALC-TI@LISTS.PPP.TI.COM]On Behalf Of Ray Kremer
Sent: Sunday, October 25, 1998 01:11
To: CALC-TI@LISTS.PPP.TI.COM
Subject: Re: numerical derivatives


The equivalent to that command on the TI-86 is nDer(.  Read about it
on page 323 of your manual.  Here's the argument structure:
nDer(expression,variable,value)
Where the 83's nDeriv command uses the optional arguement epsilon, the
86's nDer( uses the delta that is defined in the Tolerance menu at [2nd]
[MEM][F4].  Just use the default delta though, you shouldn't have to change
it.
You should keep your manual handy in case this kind of confusion occurs
again.  A lot of the commands have slight but important differences
between the 83 and 86.

>I am a high school student taking AP Calculus and working with a TI-86.
>Currently, we are working with our graphing calculators to calculate
>numerical derivatives but my teacher only knows about the TI-83, which
>doesn't help me at all.
>
>I was wondering if anyone could help me figure out derivatives with
>epsilon values different than the default .001. I know that on a TI-83,
>you would enter it as "nDeriv(expression,variable,value,epsilon)"
>but unfortunately, this process does not work on my TI-86.
>
>My teacher tried to tell us to first enter the "value,sto (the key above
>the on key),x" and then told us to enter "nDer(expression, variable,
>epsilon) but this also does not work.
References: