> It doesn't help me solve y = log10(x) Doesn't this work? (%i5) eq : y = log10(x); (%o5) y=log10(x) (%i6) log10_to_log(ex) := subst(lambda([x],log(x)/log(10)),'log10,ex)$ (%i7) log10_to_log(eq); (%o7) y=log(x)/log(10) (%i8) solve(%,x); (%o8) [x=%e^(log(10)*y)]