**Fun with the TI-80**

**TI-80 Program D2DMS - Decimal to Degrees-Minutes-Seconds**

Variables:

Decimal Format:

D = decimal

DMS Format:

H = degrees/hours, M = minute, S = seconds

INPUT “DEC:”,D

IPART D→H

IPART (60*FPART D)→M

60 * FPART (60 * FPART D)→S

DISP “H,M,S:”,H,M,S

**TI-80 Program DMS2D - Degrees-Minutes-Seconds to Decimal**

Variables:

Decimal Format:

D = decimal

DMS Format:

H = degrees/hours, M = minute, S = seconds

INPUT “H:”,H

INPUT “M:”,M

INPUT “S:”,S

H + M/60 + S/3600 → D

DISP “DEC:”,D

**TI-80 Program QUADRAT - Quadratic Equation**

Variables:

A, B, C are coefficients of the equation Ax^2 + Bx + C,
where the discriminant D:

D = B^2 – 4*A*C

If D≥0, then the roots are real and stored in X and Y.

If D<0, then the roots are complex and are in the form of
conjugates X ± Yi. X is the real part, Y
is the imaginary part.

DISP “AX^2+BX+C=0”

INPUT “A:”,A

INPUT “B:”,B

INPUT “C:”,C

B^2 – 4AC → D

DISP D

-B / (2A) → E

IF D≥0

THEN

E + √D/(2A) → X

E - √D/(2A) → Y

DISP “R1:”,X

DIPS “R2:”,Y

ELSE

E → X

√-D / (2A) → Y

DISP “RE:”,X

DISP “IM :”,Y

END

**Annuity Factors**

Variables:

I = periodic interest rate

N = number of payments/periods/deposits

**TI-80 Program USFV – Annuity Future Value Factor**

INPUT “I:”,I

INPUT “N:”,N

( (1+.01)^N – 1)/(.01I) → F

DISP F

**TI-80 Program USPV – Annuity Present Value Factor**

INPUT “I:”,I

INPUT “N:”,N

(1 – (1 + .01I)^-N)/(.01I) → P

DISP P

**Two Dimensional Vector Operations**

Let two vectors be defined as V1 = [A, B] an V2 = [C,
D]. The program calculates the dot
product, stored in E, norm of V1, stored in F, norm of V2, stored in G, and the
angle between V1 and V2 in degrees, stored in H.

**TI-80 Program VECTOR2**

DEGREE

DISP “V1:”

INPUT A

INPUT A

INPUT B

DISP “V2:”

INPUT C

INPUT D

AC + BD → E

√(A^2 + B^2) → F

√(C^2 + D^2) → G

COS^-1 (E /(F*G)) → H

DISP “NORM V1:”, F

DISP “NORM V2:”, G

PAUSE

DISP “DOT:”, E

DISP “ANGLE:”, H

**Simplistic Logistic Regression**

Fit data (x,y) to the equation:

Y = 1 / (A + B*e^(-X))

**TI-80 Program SIMPLOG**

INPUT “L1:”, L1

INPUT “L2:”, L2

e^-L1 → L1

1/L2 → L2

LINREG(aX+b) L1, L2

a→A: b→B

DISP “1/(B+Ae^X)”,A,B

PAUSE

DISP “CORR^2”,r^2

Eddie

This blog is property of Edward Shore, 2017

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