Quadratic Solver for Casio FX-3650P

[Albert Chan]

Here is a revised Quadratic Solver (85 steps), discriminant D adjustable (if better available)
Since D is shown, it's sign signal real or complex roots.

Code:

? -> A : ? -> B : ? -> C : B^2 - 4 A C -> D : 
? -> D : D >= 0 => GOTO 1 : 
-B / 2A -> X PAUSE SQRT -D / 2A -> Y PAUSE

LBL 1 : SQRT D -> Y : B > 0 => -Y -> Y : Y - B -> Y : 
2C / Y -> X PAUSE
Y / 2A -> Y

With this, and bits of work to get exact D, I can solve Cadillac Quadratic Solver, case 8
(Casio FX-3650P don't have enough precision to handle, even with reduced B, C)

Get D with previous post 1e5 trick
B^2 - 4 A C = (-22222222)^2 - 4 * 8441600 * 14624809
= (222e5 + 22222)^2 - (337e5 + 66400) (146e5 + 24809)

1e5 terms:
(222e5 + 2*22222) * 222e5 - 337e5 * 146e5 - 337e5 * 24809 - 66400 * 146e5 => 11535e5

D = (reduced B^2 - 4 A C) + (1e5 terms)
(22222^2 - 66400 * 24809) + ANS => -316

Run above:
? A -- Enter 8441600
? B -- Enter -22222222
? C -- Enter 14624809
? D -- Enter -316 (calculated D were bad, shown -1000)

-> Roots = 1.316232823 +/- 1.052904001e-6 * I