05-24-2020, 09:54 PM

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.

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