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Re: rules->function:THANKS+new plotting question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg7393] Re: rules->function:THANKS+new plotting question
  • From: Lord of Darkness <j.biddiscombe at rl.ac.uk>
  • Date: Fri, 30 May 1997 01:19:55 -0400 (EDT)
  • Organization: Rutherford Appleton Laboratory
  • Sender: owner-wri-mathgroup at wolfram.com

Thanks to all the people who replied to my rules->function question
it turns out the problem was being caused by...

soln=Solve[equation,z]
gave 
out[...]: {{z->blah blah...}}

and it was the presence of the curly brackets that was the problem.
If I put 
f[x_,y_] := Replace[Flatten[soln][[n]]]] 
(n = solution number for multiple solutions) then the problem goes away.

---------------------------
Here's a new question

If I wish to plot a function say
f[x,y] {x,xmin,xmax},{y,ymin,ymax}

then the range of values is effectively a rectangular region in (x,y)
But..
Suppose values of y do not exist for all values of x, and I wish to plot

ParametricPlot[f[x,y],{x,xmin,xmax},{y,ymin[x],ymax[x]}]

so the values of y are dependent on x - ie my solution space is no
longer a regtangular region, but some arbitrary shape depending on
ymin[] and ymax[]

How do I do that ?

Help gratefully appreciated..

John B


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