Re: plot

• To: mathgroup at smc.vnet.net
• Subject: [mg58224] Re: plot
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 23 Jun 2005 05:34:05 -0400 (EDT)
• Organization: The Open University, Milton Keynes, England
• References: <d9aups\$qe\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```David Park wrote:
> [Some of the errors mentioned come from problems with how email
>  is transmitted.  If posts are not pure ascii they can sometimes
>  contain extra spaces or = signs.  I try to detect these but it
>  it not always possible - moderator]
>
> Your code is full of errors. Many symbols are undefined so there is no way
> one could calculate a value or make a plot.  What is something like elev(r)
> supposed to mean? What is Lo=g[size] supposed to mean? In one place you type
> 'siz e' with an extra space. No piece of what you have posted makes any
> sense or will evaluate, including the very first statement.
>
> If you cleaned up your typing and provided definitions for all the symbols
> you might actually find that it worked, or at least be in a position to get
> some useful help.
>
> David Park
>
> From: Bosch, Darrell [mailto:bosch at vt.edu]
To: mathgroup at smc.vnet.net
>
> Dear Group,  Thanks to several of you for providing good suggestions to
> my previous inquiry.  In the program below I am trying to solve an
> equation for v, derive the solution with respect to size, and plot the
> resulting solution.  The problem I have is in running the plot command.
> I am trying to set numerical values for variables in the derivative
> (other than size) and plot the derivative for size, but Mathematica
> won't recognize the settings for the other values. Would appreciate any
> suggestions.  Darrell
>
>
> sol=Log[v]==-0.829923*(Log[size])+0.05652*(Log[size])^2+.000737*(Lo=
> g[siz
> e])^3-.002805*pop+.288472*(Log[elev])-.020531*soil1-.086192*soil2-.10992
> 9*Log[x]+.15501*Log[y]-.192311*Log[mall]+.024088*Log[town]+.044958*year
>
>  sol2=Solve[sol,v]
>
>  sol3=D[v /.  sol2[[1]],size]
>
>  Plot [Evaluate[sol3/. elev(r)379.82, soil1(r)0,
> soil2(r)1,mall(r)8861.89,town(r)8828.68,pop(r)5.9,x(r)24888.27,y(r)16881
> ..90,year(r)0,{size,100,1000}]]
>

Hi Darrell and Dear Group,

I apologize for misleading Darrell and perhaps some other users of this
group in my answer to Darrell?s post.

In fact, reading the messages from Jens-Peer Kuska, Bob Hanlon and David
Park, I realized that I have been tricked, I would said betrayed :-), by
my newsreader and did not catch a wrongly displayed (Log[size])^3
function that my poor brain interpreted as (Lo=g[size])^3 since it was
displayed on my screen as

(Lo=
g[siz
e])3

The fact that it could have been the Log function never occurred to me,
so the lengthy explanations about how to define the function ?g? to
something meaningful, etc.

Sorry if I have confused some people!

Best regards,
/J.M.

```

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