Fun with the TI-73 Part I: Logarithmic Regression, Percent, Square Root Simplification
TI-73 Program: LNREG - Logarithmic Regression
Introduction:
The program LNREG fits the data to the equation:
y = a * ln x + b
The lists used are:
L_1: x list
L_2: y list
Access L_1 by pressing [ 2nd ] [ STAT ] (LIST), 1.
Access L_2 by pressing [ 2nd ] [ STAT ] (LIST), 2
You can edit lists by pressing [LIST].
The lower case a and b are from the VARS, Statistics, EQ menu.
Program:
"EWS 2021"
Disp "FIT Y=A LN X +B","USES X=L1,Y=L2:
ln(L_1) → L_1
LinReg(ax+b) L_1,L_2
a → A
b → B
Output(4,1,"A=")
Output(4,5,A)
Output(5,1,"B=")
Output(5,5,B)
Output(6,5,r²)
e^(L_1) → L_1
Pause
Menu("PLOT?","YES",1,"NO",2)
Lbl 1
PlotsOff
FnOff
"A*ln(X)+B"→Y_1
Plot1(xyLine,L_1,L_2,□)
ZoomStat
Lbl 2
Example:
X: L_1 = {1, 2, 3, 4, 5, 6}
Y: L_2 = {-1.26, 2.1018, 4.0683, 5.4635, 6.5458, 7.43}
Results:
y = A ln x + B
A = -1.259978557
B = 4.849985251
r^2 ≈ 1
TI-73 Program: PERCENT - Percent Calculations
Introduction:
The program gives the users four options:
1. Adding tax (plus percent)
2. Subtracting tax (minus percent)
3. Percent Change
4. Percent Total
The percent key divides the amount by 100. Example: 5% turns to 0.052.
Program:
"EWS 2021"
Menu("PERCENT","TAX+",1,"TAX-",2,"%CHG",3,"%TOT",4)
Lbl 1
Prompt N
Input "X% ",X
N*(1+X%)→Y
Pause Y
Stop
Lbl 2
Prompt N
Input "X% ",X
N*(1-X%)→Y
Pause Y
Stop
Lbl 3
Input "OLD=",O
Input "NEW=",N
(N-O)*100/O→Y
Pause Y
Stop
Lbl 4
Input "PART=",P
Input "WHOLE=",W
100*P/W→Y
Pause Y
Stop
Example:
TAX+: Add 15% to 19.95
N: 19.95, X%: 15
Result: 22.9425
TAX-: Subtract 15% from 19.95
N: 19.95, X%: 15
Result: 16.9575
%CHG: Old (O): 11700, New (N): 15420
Result: 31.79487179
%TOT: Part (P): 11700, Whole (W): 15420
Result: 75.7548638
TI-73 Program: SQROOT - Simplification Square Root
This program tries to factor √N to A√B. N, A, and B are integers.
Program:
"EWS 2021"
Disp "√(N)->A√(B)"
Prompt N
iPart(√(N))→X
While X≠0
If fPart(N/X^2)=0
Then
X→A
N/X^2→B
Goto 1
Else
X-1→X
End
End
Lbl 1
Disp "A=",A,"B=",B
Pause
Examples:
N = 88; √88 = 2√22
N = 1225; √1225 = 35√1
Notes:
* There is no ALPHA key for the TI-73 (family). Text is entered by use of the [ 2nd ] [ MATH ] (TEXT) key sequence. Letters are selected by using the arrow keys and selecting them with the ENTER key.
* The underscore character ( _ ) acts like a space.
* The TEXT has the letters A-Z, _, <, =, >, ≤, ≠, ≥, and the logic functions and, or. For the question mark character, ?, press [ 2nd ] [ PRGM ] (CATALOG) [ ↑ ] [ ENTER ].
* The programming language of the TI-73 is the robust as the TI-83 family (TI-83, TI-83 Plus, TI-84 Plus family, TI-82).
* The main difference is that results are shown on a separate screen for output. When a program terminates, the TI-73 returns to the Home screen. It is necessary to include a Pause at the end to keep the results on the screen.
Stay tuned tomorrow for more programs for the TI-73.
Eddie
All original content copyright, © 2011-2021. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.
