teaching Maxima logarithms



On Wed, 2013-05-15 at 18:04 -0700, Bill Eaton wrote:
   . . .
> That definitely works, but my desire is to strip off any vestiges of e or
> log(10) in the output. What I would really like to see is:
>   (%o8) [x=10^y)]
> or more generally
>   (%o8) [x={base n}^y] 

For What It's Worth, which is probably not so much, we can get close:

  (%i1) display2d:false$

  (%i2) eq : y = log10(x);

  (%o2) y = log10(x)
  (%i3) log10_to_log(ex) := subst(lambda([x],log(x)/log(10)),'log10,ex)$

  (%i4) log10_to_log(eq);

  (%o4) y = log(x)/log(10)
  (%i5) solve(%,x);

  (%o5) [x = %e^(log(10)*y)]
  (%i6) x = radcan(part(%o5,1,2));

  (%o6) x = 2^y*5^y

RADCAN overshot just a little, but at least there's no log10 or %e.  I
have no idea whether this generalizes, or how.

-- 
Bill Wood