TI-65 Programs Part I: Digital Root, Complex Number Multiplication, Dew Point

TI-65 Programs Part I:  Digital Root, Complex Number Multiplication, Dew Point

Recently working with the HP-71B and Radio Shack EC-4004, I am feeling the 1980s vibes and staying in the decade for the 1987 classic calculator Texas Instruments TI-65.   

Some background information of the TI-65 (provided by Datamath):  http://www.datamath.org/Sci/Galaxy/TI-65.htm

Did you know the TI-65 has a timer?  Click here to see a video demonstration!

This is the first part of programs for the TI-65 for this Fourth of July.    

Click here for Part II:  Reynold’s Number/Hydraulic Diameter, Escape Velocity, Speed of Sound/Resonant Frequencies in an Open Pipe

Click here for Part III:  Impedance and Phase Angle of a Series RLC Circuit, 2 x 2 Linear System Solution, Prime Factorization

TI-65 Digital Root

Takes the digital root of an integer.  To find the digital root:

1.  Add up the number’s digits.

2.  The sum is over 10, add the digits again.

3.  Repeat step 2 until you get a single digit.

Or alternatively, use the formula dr(n) = 1 + ((n-1) mod 9) = n – 9 * intger((n-1)/9)

Program:

CODE	STEP	KEY
12.0	00	STO 0
49	01	-
9	02	9
38	03	*
16	04	(
16	05	(
13.0	06	RCL 0
49	07	-
1	08	1
17	09	)
28	10	÷
9	11	9
17	12	)
2nd 27	13	ITNG
14	14	=
51	15	R/S

Input:  Enter integer, press [RST] [R/S]

Test 1:  dr(1555) = 7

Test 2:  dr(38267) = 8

TI-65 Complex Multiplication

(a + bi)*(c + di) = (r1*r2) * e^(i*(θ1 + θ2))

Where r1 ∠ θ1 is the polar form of a + bi and r2 ∠ θ2 is the polar form of c + di.

Program:

CODE	STEP	KEY	COMMENT
44	00	X<>Y	Start with a
51	01	R/S	Prompt for b
-2nd 22	02	INV 2nd P-R	Convert to Polar
12.1	03	STO 1
44	04	X<>Y
12.0	05	STO 0
51	06	R/S	Prompt for c
44	07	X<>Y
51	08	R/S	Prompt for d
-2nd 22	09	INV 2nd P-R	Convert to Polar
12.59	10	STO+
1	11	1	STO+ 1
44	12	X<>Y
12.38	13	STO*
0	14	0	STO* 0
13.0	15	RCL 0
44	16	X<>Y
13.1	17	RCL 1
2nd 22	18	2nd P-R	Convert to Rectangular
51	19	R/S	Display imaginary part of product
44	20	X<>Y
51	21	R/S	Display real part of product

(a + bi)*(c + di) = x + yi

Input:  a [RST] [R/S], b [R/S], c [R/S], d [R/S]

Output:  y [R/S], x

Test 1:  (5-3i)*(4+i):

5 [RST] [R/S]. -3 [R/S], 4 [R/S], 1 [R/S]

Result:  -7 [R/S] 23,   23-7i

Test 2:  (-6+3i)*(2 + 2i)

Result:  -18 – 6i

TI-65  Dew Point Calculation

This program accepts input and displays dew point in degrees Fahrenheit (°F).

Source for formula:    http://ag.arizona.edu/azmet/dewpoint.html

CODE	STEP	KEY	COMMENT
3rd 28	00	3rd °F-°C	Convert to °C
12.0	01	STO 0
38	02	*
1	03	1
7	04	7
57	05	.	Decimal Point
2	06	2
7	07	7
12.1	08	STO 1
28	09	÷
16	10	(
2	11	2
3	12	3
7	13	7
57	14	.	Decimal Point
3	15	3
12.2	16	STO 2
59	17	+
13.0	18	RCL 0
17	19	)
59	20	+
51	21	R/S	Prompt for h
32	22	LN
39	23	=
28	24	÷
13.1	25	RCL 1
39	26	=
12.1	27	STO 1
38	28	*
13.2	29	RCL 2
28	30	÷
16	31	(
1	32	1
49	33	-
13.1	34	RCL 1
17	35	)
39	36	=
-3rd 28	37	INV 3rd °F-°C	Convert to °F
51	38	R/S

 Input:  Enter temperature in °F [RST] [R/S], enter humidity (as a decimal) [R/S]

Output:  Dew Point in °F

Test 1:  temperature = 68°F,  humidity = 0.5  (50%)

68 [RST] [R/S], 0.5 [R/S]

Result:  dew point ≈ 48.68533155°F

Temp 2:  temperature = 93°F, humidity = 0.35

Result:  dew point ≈ 61.29167421°F

Happy Birthday United States!

This blog is property of Edward Shore, 2016.