## 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.

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.

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