logx y - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: logx y (/thread-74875.html) |
logx y - GWB - 06-10-2005 Logarithm of y to base x ... There'll never be a logxy key; besides, it is not needed. But just for fun let's try to write a tiny program for this, the tiniest the best. (logyx can be done in only four steps: LN x<>y LN /, but this entry order doesn't look so natural. However logxy in four steps is still possible on most calculators). Regards, Gerson.
Re: logx y - Tom Sherman - 06-12-2005 Hi Gerson, Nice problem. Maybe this: (LN) (x root of y) (LN) or: (LOG) (x root of y) (LOG) Cheers, Tom
BINGO! (Re: logx y) - GWB - 06-12-2005 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:
Cheers,
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