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Re: Log(ln) Function + 2 Parameters + Greater

  • To: mathgroup at smc.vnet.net
  • Subject: [mg89297] Re: Log(ln) Function + 2 Parameters + Greater
  • From: Felipe Mannshardt <vexie.infamous at googlemail.com>
  • Date: Wed, 4 Jun 2008 05:37:27 -0400 (EDT)
  • References: <g22tp5$ikl$1@smc.vnet.net> <g237ef$q4d$1@smc.vnet.net>

dh wrote:
> Hi Felipe,
> 
> why are you not simply using an If[] statement:
> 
> If[a>0, Plot[...]]
> 
> hope this helps, Daniel
> 
> 
> 
> Felipe Mannshardt wrote:
> 
>> Hello,
> 
> 
>> i am having problem telling Mathematica to:
> 
> 
>> First Try,
> 
> 
>> Clear[x, f]
> 
>> f[x_] := x (a + Log[x])^2
> 
> 
>> a > 0
> 
>> Plot[f[x], {x, -5, 5}]
> 
> 
>> Second Try,
> 
> 
>> f[x_] := x (a + Log[x])^2
> 
> 
>> Plot[f[x], {x, -5, 5}] /.a-> a>0
> 
> 
> 
>> What i want is to tell Mathematica to draw a Graph of f[x] when a>0
> 
> 
>> Thanks for the help.
> 
> 
> 
> 
> 
> 

Thanks for all replies, worked for my last function, but the suggestions 
you guys made so far did work with my last function, but now i have a 
new one, and i am here just playing around and i am unable to get it 
drawn :(

First to the first Function, i believe the best suggestion was the use 
of "if",

But, i can not get it to work :/

Clear[x, f, a]
f[a_][x_] := x (a + Log[x])^2
If[a > 0, Plot[f[x], {x, 0, 2}]]

And all suggestions also did not work at all for my new Function,

f[a_][x_] := (x/E^(ax));
Plot[Table[f[a, x], {a, 0, 2}], {x, 0, 3}]

What am i doing wrong ?

I have already drawn this function by hand,
and i have two types of function,
for a>0 and a<0

But i can not figure out how to draw it in Mathematica :(

Sorry, that i ask so "noob/dumb" questions, but i have already tried 
looking in the help and it did not help me further in this problem, so i 
believe the best is asking, right ?


Thanks a Lot.


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