Re: entering an equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg21629] Re: [mg21592] entering an equation*From*: "Tomas Garza" <tgarza at mail.internet.com.mx>*Date*: Tue, 18 Jan 2000 02:35:16 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Mark Woolard [mark at ratbyte.com] wrote: > I am trying to plot a series of functions in Mathematica...one is > giving me > trouble. I need : ln2 (ln2 x) > > I enter: Log[2, Log[2,x]] > > and I get: > > is not a machine-size real \ > number at \!\(x\) = \!\(4.1666666666666667`*^-7\)." > > Does anyone have any suggestions? Yes. The range over which you wish to plot is important. Try, for example: In[1]:= Plot[Log[2, Log[2, x]], {x, 1, 2}] The plot is OK. Look at the values of ln2 (ln2 x) in the neighborhood of 1 + 0: In[2]:= Table[Log[2, Log[2, x]], {x, 1, 2, 0.1}] Out[2]= {-Infinity, -2.86246, -1.92668, -1.40159, -1.04267, -0.773584, -0.56049, \ -0.38546, -0.237869, -0.110917, 0.} Tomas Garza Mexico City