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mchris · (This post was last modified: 05-04-2023 09:13 PM by mchris.)

Probably someone has done it before, but...
Inspired by a HP41C program I found for the quadratic formula that uses only the 4 level stack, no INPUTs, no extra registers, I thought maybe I could do something similar with the HP35s, despite that it doesn't have the register arithmetic with the stack registers. The program uses the equivalent formula -(b/2a)±SQRT((b/2a)^2-(c/a)). The fact there is only 2 terms makes it easier. I don't think it could be done with the (-b±SQRT(b^2-4ac))/2a formula. We press a ENTER b ENTER c XEQ Q and the 2 solutions, real or complex returned in X and Y registers. No INPUTs, no extra registers, just the stack, in just 29 steps.

Code:

Q001        LBL Q

Q002        EQN REGZ

Q003        /

Q004        RDN

Q005        X<>Y

Q006        /

Q007        2

Q008        /

Q009        +/-

Q010        ENTER

Q011        X^2

Q012        RUP

Q013        -

Q014        X>=0?

Q015        GTO Q021

Q016        +/-

Q017        SQRT

Q018        i

Q019        *

Q020        GTO Q022

Q021        SQRT

Q022        ENTER

Q023        ENTER

Q024        EQN REGT

Q025        +

Q026        RDN

Q027        -

Q028        RUP

Q029        RTN