## Thursday, July 12, 2018

### Fun with the Radio Shack EC-4026

Fun with the Radio Shack EC-4026

(Equivalent of the Casio fx-4500P)

Programming Notes

The syntax for prompting for variables and displaying results are slightly different from the usual Casio programming language (as I mentioned, the EC-4026 is a clone of the fx-4500P).  Check out the unusual If-Then-Else-End structure as well.

Prompting Syntax:
{var} : var “prompt string”

Example:
{X}: X”ENTER X”

Display Syntax:
Calculation
“Display string”   (solid right triangle, [2ndF] [↑])

Example:
X
“F(X)=”

The If-Then-Else-End Structure:
If condition do if the condition is true do if condition is false   (clear right triangle, [2ndF] [√])

Note:  I symbolize the [x^y] by ^.

Finding the Monthly Payment of a Mortgage with Total Interest Paid and Total Cash Outflow

Program MORTGAGE:

L1  Fix 2
L2 {A}: A”LOAN AMOUNT”
L3 {Y}: Y”YEARS”
L4 {I}: I”RATE”
L5 I = I/1200
L6 N = Y*12
L7 P = A*(I(1+I)^N)/((1+I)^N-1)
L8 “MONTHLY PMT”
L9 N*P
L10 “OUTFLOW”
L11 N*P-A
L12 “TOTAL INTEREST”
L13 Norm

Example:

A:  Loan is \$250,000.00
Y:  30 years
I: Interest rate of 4%

Results:

P:  Payment:  \$1,193.59
Outflow:  \$429,673.77
Total Interest:  \$179,673.77

Midlength, Height, and Area of a Trapezoid

Program TRAPEZIOD:

L1 {A}
L2 {B}
L3 {C}
L4 {D}
L5 H = √((-A+B+C+D)*(A-B+C+D)*(A-B+C-D)*(A-B-C+D))/(2*Abs(B-A))
L6 M = (A+B)/2
L7 K = M*H
L8 M
L9 “MIDLENGTH”
L10 H
L11 “HEIGHT”
L12 K
L13 “AREA”

Quadratic Equation A*x^2 + B*x + C = 0

L1 {A}: A”A”
L2 {B}: B”B”
L3 {C}: C”C”
L4 D = B^2-4*A*C
L5 D<0 Goto 1
L6 X = (-B + √D)/(2A)
L7 Y = (-B - √D)/(2A)
L8 Goto 0
L9 Lbl 1
L10 X = -B/(2A)
L11 “REAL”
L12 Y = √(Abs D)/(2A)
L13 “IMAG”
L14 Lbl 0
L15 “DONE”

Example:

3x^2 + 6x – 1 = 0; A = 3, B = 6, C = -1
Result:  0.154700538, -2.154700538

3x^2 + 6x + 10 = 0; A = 3, B = 6, C = 10
Result:  REAL: -1, IMAG: 1.527525232.  -1 ± 1.527525232i

Minimum Loss Matching

Variables:

Input: Y = Z0, Z = Z1

Output:

R = R1
S = R2
L = Loss Marching

Program MINLOSS:

L1 1:  “Z1<Z0”
L2 {Y}: Y”Z0”
L3 {Z}: Z”Z1”
L4 L = √(1 – Z/Y)
L5 R = Y*L: “R1”
L6 S = Z/L: “R2”
L7 L = 20 log (√(Y/Z) + √(Y/Z – 1)): “LOSS”

Example:

Input:

Y: Z0: 15
Z: Z1: 10

Output:

R1: 8.66025 Ω
R2:  17.32051 Ω
Loss:  5.71948

Polar and Rectangular conversions

 Variable Rectangular Results Polar Results V x r W y θ

L1 {R}: R”R1”
L2 {S}: S”ANG1”
L3 Rec(R,S)
L4 R = V: S = W
L5 {V}: V”R2”
L6 {W}: W”ANG2”
L7 Rec(V,W)
L8 R = R+V: S = S+W
L9 Pol(R,S)
L10 V: “R SUM”
L11 W: “ANG SUM”

Example:

4 20° + 3 11 ° (In Degrees Mode)

Result (rounded to 4 digits): 6.9789 16.1442°

How to Handle a Tax Bracket (Simple Sample)

Take a sample (and simplified) tax bracket, where income is X:

0 < X ≤ 200:  tax rate is 10% of X
200 < X ≤ 600:  tax rate is 13% of X
600 < X: tax rate is 16% of X

Program:

L1 {X}: X”X”
L2 X > 600 P = 16: Goto 1
L3 X > 200 P = 13: Goto 1
L4 P = 10
L5 Lbl
L6 X * P/100

Eddie

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