Re: entering an equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg21608] Re: [mg21592] entering an equation*From*: "David Park" <djmp at earthlink.net>*Date*: Sun, 16 Jan 2000 22:43:53 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

>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? > Mark, Plot[Log[2, Log[2, x]], {x, 1.0, 10}]; works but Plot[Log[2, Log[2, x]], {x, 0.99, 10}]; does not work because you are trying to take a log of a negative number over the first part of the range. Mathematica will produce the plot over the domain where the function is real. So you can either ignore the error messages, or turn them off, or restrict your plotting domain to a proper range of numbers which give only real and not complex results. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/