Double factorial [wp34s]

[Gerson W. Barbosa]

(02-12-2016 07:54 PM)Dieter Wrote:  

(02-12-2016 02:21 PM)Gerson W. Barbosa Wrote:  The following preverves the Y register, but I need two more steps:

Simply replace the initial ENTER ENTER || with #1/2 RCLx Y and it's one step less again. ;-)

That's it! Thanks again!

(02-12-2016 07:54 PM)Dieter Wrote:  

(02-12-2016 02:21 PM)Gerson W. Barbosa Wrote:  Ideally, both Y and Z stack registers should be saved. Thus I would not need the alternative definition in program 01.

Hmmm... this sounds quite challenging. Which does not mean it couldn't be done. ;-)

Why not using register I? Its content would be changed in the next complex operation anyway. Or does this look like cheating? :-)

Code:


0001 **LBL A
0002 z[<->] I
0003 # 1/2
0004 RCL[times] Y
0005 2[^x]
0006 RCL L
0007 x!
0008 [times]
0009 x[<->] Y
0010 (-1)[^x]
0011 DEC X
0012 # 004
0013 /
0014 CNST 86
0015 x[<->] Y
0016 y[^x]
0017 [times]
0018 RCL I
0019 [<->] YZXX
0020 RTN