logx y

[GWB]

Logarithm of y to base x ... There'll never be a log_xy key; besides, it is not needed. But just for fun let's try to write a tiny program for this, the tiniest the best.
On the 32Sii and the 33S only three steps will do the job. Anyone want to try?

(log_yx can be done in only four steps: LN x<>y LN /, but this entry order doesn't look so natural. However log_xy in four steps is still possible on most calculators).

Regards,

Gerson.

[Tom Sherman]

Hi Gerson,

Nice problem. Maybe this: (LN) (x root of y) (LN)

or: (LOG) (x root of y) (LOG)

Cheers, Tom

[GWB]

Hi Tom,

Congratulations! Most likely you have made use of mathematical properties of logarithms to solve the problem. In fact, it can be shown that lny/lnx=ln(y^(1/lnx)). I must confess I found this out entirely by chance, playing with the 32Sii keyboard for a while. On the 33S my unorthodox method would have been even easier, as the [x xroot y] is not a shifted key :-)

Thanks for your having appreciated the problem.

For other HP scientific calcs (except the HP-35): [LN] [1/x] [y^x] [LN]

Check this link out:

http://groups-beta.google.com/group/comp.sys.hp48/browse_frm/thread/69bb904223c14c0e/eb07a514032b8587?q=LN+XROOT+LN&rnum=1#eb07a514032b8587

Cheers,
Gerson.