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Gerson W. Barbosa · 05-28-2014, 04:18 AM

(05-27-2014 06:57 PM)Thomas Klemm Wrote:
(05-27-2014 05:30 PM)Jeff_Kearns Wrote: Can you think of a way of dramatically shortening it, (...) so that it still gives real and complex roots?

Copied most of it from here: Short quadratic solver (HP-15C)

Code:

Q01 LBL Q Q02 ENTER Q03 R^ Q04 / Q05 R^ Q06 LASTx Q07 / Q08 2 Q09 +/- Q10 / Q11 ENTER Q12 ENTER Q13 x^2 Q14 R^ Q15 - Q16 SQRT Q17 ENTER Q18 +/- Q19 CMPLX- Q20 RTN

Doesn't give you the complex solution but that should be easy to add. There are probably shorter solutions possible by using a register.

Cheers
Thomas

Nice use of CMPLX- for saving a step or two!

This might do while we don't think of something better:

Code:

Q01 LBL Q

Q02 CF 1

Q03 ENTER

Q04 R^

Q05 /

Q06 R^

Q07 LASTx

Q08 /

Q09 -2

Q10 /

Q11 ENTER

Q12 ENTER

Q13 x^2

Q14 R^

Q15 -

Q16 x<0?

Q17 SF 1

Q18 ABS

Q19 SQRT

Q20 FS? 1

Q21 RTN

Q22 ENTER

Q23 +/-

Q24 CMPLX-

Q25 RTN

If the roots are complex, the flag 1 announciator will be lit and the real and complex parts will be in registers Y and X, respectively.

Cheers,

Gerson[/code]