TI-74 Programming: Factorial, List of
Random Integers, 2 x 2 Matrix Determinant and Inverse, Simple Pendulum, Secret
Codes
Note: The TI-74 has one programming space (lines 0
to 32768), which the entire space can be saved if the TI-74 connected to an
appropriate peripheral (cassette or computer).
Cassettes? The TI-74 is a 1980s
basic computer after all.
TI-74 Program Factorial
The TI-74 does
not have a factorial function its command set.
Here is one way to tackle it:
1300 !
Factorial
1310 INPUT “N=”;
N
1320 IF N=0
THEN PRINT 0: PAUSE: STOP
1325 F=1
1330 IF I=1 TO
N-1
1340 F=F*I
1350 NEXT I
1360 PRINT “N!=”;
F: PAUSE
1370 END
TI-74 List of Random Integers
Integers will
appear for 2 seconds followed by a “Next…” indicator.
1000 ! List of random
integers
1005 RANDOMIZE
1010 INPUT “Length?”;
K
1020 INPUT “High
Number:”; N
1025 FOR I=1 TO
K
1035 PRINT INT(N*RND+1):
PAUSE 2
1040 PRINT “Next…”:
PAUSE 0.5
1045 NEXT I
1050 PRINT “Done”:
PAUSE: END
TI-74 2 x 2 Matrices:
Determinant and Inverse
Matrix: [[A, B],[C, D]]
Inverse: [[F, G],[H, I]]
Determinant: E
= A*D – B*C. If E=0, the matrix is
singular.
1100 ! 2 x 2
Matrices; det/inv
1105 INPUT “A=”;
A, “B=”; B
1110 INPUT “C=”;
C, “D=”; D
1115 E=A*D-B*C
1120 PRINT “det=”;
E: PAUSE 2
1125 IF E=0
THEN STOP
1130 PRINT “inv=”:
PAUSE 2
1135 F = D/E: G
= -B/E: H=-C/E: I=A/E
1140 PRINT “F=”;
F: PAUSE 2
1145 PRINT “G=”;
G: PAUSE 2
1150 PRINT “H=”;
H: PAUSE 2
1155 PRINT “I=”;
I: PAUSE 2
1160 END
Example:
Matrix: [[1, 5],[-2, 7]]
A=1, B=5, C=-2, D=7
RUN 1100:
det = 17
inv =
F = .4117647059
G =
-.2941176471
H = .1176470588
I = .0588235294
TI-74 Simple Pendulum: Angular Velocity and Period
This routine
calculates the angular velocity and period for a simple pendulum. SI units are used, meaning that g = 9.80665
m/s^2. Note the SQR command is square
root.
1200 ! Simple
Pendulum, SI unites
1205 G=9.80665
1210 INPUT “Length
(m):”; L
1215
W=SQR(G/L): T=2*PI*SQR(L/G)
1220 PRINT “Angular
Vel.:”; W; “m/s”: PAUSE
1225 PRINT “Period:”;
T; “s”: PAUSE
1230 END
Example: L = 1.14 m
Results: W = 2.932971967 m/s, T = 2.1422588902 s
TI-74 Secret 3 Digit Codes
I learn the
PRINT USING and IMAGE commands for the first time here. On the TI-74, # is a number field, the period
(.) is the decimal point, ^ is the exponential character, and I can use spaces
and text. Yes, IMAGE is different on each
of the basic calculators.
500 IMAGE ###
### (3 spaces in between the
sets of hashtags)
505 PRINT “Here are the”: PAUSE 1
510 PRINT “secret codes!”: PAUSE 1
515 FOR I=1 TO 4
520 A=100*RND:
B=100*RND
525 PRINT USING
500; A,B : PAUSE 1
530 NEXT I
540 END
Notes
1.
I am not able to use a variable while using a
DIM command to size an array. This is
not allowed:
100 Z = 10
110 DIM A(Z)
2.
The commands and one-letter variables auto-capitalize
when [ENTER] is pressed. For example:
I type 100 print a, press [ENTER] and when look at the line again, the TI-74
displays:
100 PRINT A
3.
It is a good idea to put an END command after
each routine. END will tell the TI-74
stop, allowing multiple, separate routines in the TI-74 programming space.
4.
The
amount of free memory is found by the formula:
FRE(0)-FRE(1). The keyboard
shortcut to FRE is [FN] [ ↓ ].
5.
If
you want to clear the entire program space, type NEW ALL.
There will be
more TI-74 programs in the near future.
Until next time,
Eddie
This blog is
property of Edward Shore, 2016.
