Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Courses » ap-calculus

Topic: Parametric tables for TI-85
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  
Dave Slomer

Posts: 244
Registered: 12/6/04
Parametric tables for TI-85
Posted: Nov 9, 1997 5:45 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Someone was wondering how to use TI-85 to help students see limits
numerically. Having already done this on the 92 and 86, I thought it should
be doable on the 85, since I had revised a program from Marco Radzinschi
awhile ago to do normal tables.

The idea is to use geometric approach behavior for x so that F(x)
approaches its limit (if any) faster. One needs to define A and F(x) before
using the program and to set up the parametric editor.

Here's that program, one you run maybe once, and then save as a graph
database called LIM, which will need to be recalled before running the
table program. Also, the desired functions would need to be selected
afterward:
:xt1=A-.5^t
:yt1=evalF(F,x,xt1)
:xt2=A+.5^t
:yt2=evalF(F,x,xt2)
:xt3= -10^t
:yt3=evalF(F,x,xt3)
:xt4= 10^t
:yt4=evalF(F,x,xt4)
:FnOff
:0 STOREINTO tMin
:9 STOREINTO tMax
:1 STOREINTO tStep
:StGDB LIM

And here's the param table program, APTABLE:
:Param
:int((tMax-tMin)/tStep+1) STOREINTO K
:Disp K
:dimL eval tMin STOREINTO TC
:{K,TC} STOREINTO dim T
:For(t,tMin,tMax,tStep)
: li CONVERTTO vc eval t STOREINTO T(K)
:End
:T TRANSPOSE STOREINTO T
:For(I,1,TC,2)
: T(I)- SQUAREROOT(-1)*T(I+1) STOREINTO T((I+1)/2)
:End
:{TC/2,K} STOREINTO dim T
:T TRANSPOSE STOREINTO T
:Pause T

Here's an unnecessary program which might help define F and A correctly:
:InpSt "F(x)=",FS
:St CONVERTTO Eq(FS,F)
:Prompt A
:Disp "Select functions,"
:Disp "then run APTABLE."
It is unnecessary because F and A can easily be defined on the home screen:
F=sin x/x
0 STOREINTO A
APTABLE

STOREINTO is the "store arrow", above the ON key.
TRANSPOSE is the "little T exponent-looking thing" found in MATRIX MATH F2.
And CONVERTTO is the "filled in triangle" which is part of the LI>VC and
ST>EQ commands which are found in LIST MORE F4 and STRING F5.

I think I'll store this on my web page,
http://www.geocities.com/capecanaveral/lab/8692,
as a zipped group file (APTABLE.85G) in case anyone wants it.

Ah, what fun it was!

Dave Slomer
AP Calculus and computer science teacher
Winton Woods HS, Cinti, OH 45240




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.