Self-teaching snag

*To*: mathgroup at smc.vnet.net*Subject*: [mg74556] Self-teaching snag*From*: Todd Allen <genesplicer28 at yahoo.com>*Date*: Mon, 26 Mar 2007 02:04:14 -0500 (EST)

Hi All, I am trying to refresh my skills in basic problem solving using Mathematica, but am running into some difficulties which are beginning to make me suspicious of Mathematica itself. (I probably should be suspicious of my own brain...but you know how that is :-) Here is the scenario: I have written a basic function to tell me what percentage of battery power will remain in a battery after x number of days, provided that we start with a full charge and lose 5% of that charge per day. If you execute the following code in Mathematica (V5.1): charge[0]=1.0 (* 100% *); charge[day_]:=(charge[day-1]-(0.05*charge[day-1])); charge[20] I receive an output of 0.358486 for my query at the 20 day mark.....so, no problem so far. However, when I try to ask for the output at charge[35], mathematica seems to enter an endless calculation. I've let the computer run for as long as 5 minutes without getting an answer. Is there something wrong with my function, my version of Mathematica or something else I haven't considered? Additionally, When I try the following: In[145]:= Solve[charge[day]==0.15,day]; Mathematica gives me the error: "$RecursionLimit::reclim: Recursion depth of 256 exceeded." I am trying to ask Mathematica to tell my how many days it takes to reduce the battery power to 15 percent, but I must be messing something up?? If anyone has any pointers, I'd certainly appreciate it, because I am a little stuck right now. Best regards, Todd Allen ____________________________________________________________________________________ We won't tell. Get more on shows you hate to love (and love to hate): Yahoo! TV's Guilty Pleasures list. http://tv.yahoo.com/collections/265

**Follow-Ups**:**Re: Re: Self-teaching snag***From:*"Chris Chiasson" <chris@chiasson.name>

**Re: Self-teaching snag***From:*Daniel Lichtblau <danl@wolfram.com>

**Re: Self-teaching snag***From:*leigh pascoe <leigh@cephb.fr>

**Re: Self-teaching snag***From:*"Chris Chiasson" <chris@chiasson.name>

**Re: Self-teaching snag***From:*Murray Eisenberg <murray@math.umass.edu>

**Re: Self-teaching snag***From:*gardyloo <gardyloo@mail.wsu.edu>

**Re: Self-teaching snag***From:*Stern <nycstern@gmail.com>

**Re: Self-teaching snag***From:*"Chris Chiasson" <chris@chiasson.name>

**Re: Self-teaching snag***From:*"Matthias Bode" <lvsaba@hotmail.com>