(35s) Stack-only quadratic solver

[Liam Hays]

I know, I know, this is another quadratic equation solver for the 35s. This one, though, is a little different in two ways: a) it operates fully in the stack, modifying no variables, and b) it doesn't use any equations, so while it has more lines, it should theoretically be faster as well.

I also know this isn't one of the awesome high-performance solvers, but figuring out all the stack manipulation was a fun challenge and I'm proud of what I've made. It will find complex roots.

Usage: enter a, b, and c onto the stack, in that order, and XEQ Q (or whatever label you choose). You'll get the roots back, or if there's one root, that root on both the X and Y levels.

The checksum on my machine is 2F04, with a length of 160.

Code:

Q001 LBL Q
Q002 Rdown
Q003 x^2
Q004 Rup
Q005 4
Q006 *
Q007 Rup
Q008 *
Q009 ENTER
Q010 Rdown
Q011 Rdown
Q012 rootx
Q013 ENTER
Q014 x^2
Q015 Rup
Q016 -
Q017 x<0?
Q018 GTO A020
Q019 GTO A025
Q020 ABS
Q021 rootx
Q022 i
Q023 *
Q024 GTO A026
Q025 rootx
Q026 ENTER
Q027 Rdown
Q028 Rdown
Q029 +/-
Q030 ENTER
Q031 Rup
Q032 +
Q033 LASTx
Q034 x<>y
Q035 Rdown
Q036 -
Q037 x<>y
Q038 /
Q039 ENTER
Q040 Rdown
Q041 Rdown
Q042 LASTx
Q043 /
Q044 2
Q045 /
Q046 Rdown
Q047 Rdown
Q048 2
Q049 /
Q050 Rup
# swap to make output like the three-var one
Q051 x<>y
Q052 RTN

Try it out: say we want to solve 4*x^2 - 8*x + 3 = 0. To do this, you would follow these steps:

Code:

4 [ENTER] -8 [ENTER] 3
XEQ Q

The screen should read -0.5 and -1.5.