Monday, July 4, 2016

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


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).


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.

2 comments:

  1. Hi Eddie,

    Have you got any information about how to repair LCD of this amazing calculator?! I buy one on a Hungarian auction site (the seller said the unit is not working - I know that the battery replacement is little tricky and maybe the seller do not know that and I was right).

    So, everything is works but on the LCD some annunciator is not shows. It is possible to fix it?!

    Csaba

    ReplyDelete
  2. Another little thing: Maybe this is the slowest calculator on the world?!

    Csaba

    ReplyDelete

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