Re: odd mathematica blindspot

*To*: mathgroup at smc.vnet.net*Subject*: [mg56472] Re: [mg56468] odd mathematica blindspot*From*: yehuda ben-shimol <bsyehuda at gmail.com>*Date*: Tue, 26 Apr 2005 21:52:28 -0400 (EDT)*References*: <200504260533.BAA14442@smc.vnet.net>*Reply-to*: yehuda ben-shimol <bsyehuda at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, First Mathematica solves it with no problem. I wonder which version you are using. I tested it on ver. 5.1 on Win XP. Second, the (rather simple) problem is Solve[a^x==b,x] will return {{x->Log[b]/Log[a]}} so if you assign sol = Solve[a^x==b,x]; you can check it for many values of a and b which in your case will lead to sol={{x->-Log[2]/Log[(999999999999/10000000000000)]}} to extract this value you need to use replacement rules x/. sol[[1]] will give you the number x/.sol will give you the number as a list of a single element. yehuda On 4/26/05, Edward Peschko <esp5 at pge.com> wrote: > hey all, > > I was wondering why the following didn't output any solutions. I'd think > it would be easy: > > Solve[(999999999999/10000000000000)^x == .5, x] > > It gives no solutions. What's really odd is when you say: > > Solve[(999/1000)^x==.5, x] > > which *does* give solutions, in the form: > > {{x -> 692.801... }} > > Also, just curious, but how do you extract 'x' from the above? > Say I wanted to plug the above solution into another equation.. > In perl I'd say something like: > > y = Solve[(999/1000)^x == .5, x]; > > 3 * y->{x} # replaces with 692.81 > > etc. etc. > > but this doesn't seem to work. How do you access parts of a mathematica > datastructure/hash? > > And finally, how do you set values with the tty? ie: suppose my backspace and > delete key aren't working with math.exe (they aren't) and I want them to > delete typos. In unix this would be stty erase ^H. In mathematica...? > > Thanks much for any help, > > Ed > >

**Follow-Ups**:**Re: Re: odd mathematica blindspot***From:*Edward Peschko <esp5@pge.com>

**References**:**odd mathematica blindspot***From:*Edward Peschko <esp5@pge.com>