ContourPlot non rectangular evaluation?

• To: mathgroup at smc.vnet.net
• Subject: [mg127833] ContourPlot non rectangular evaluation?
• From: Sam McDermott <samwell187 at gmail.com>
• Date: Sat, 25 Aug 2012 04:26:41 -0400 (EDT)
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Hi,

I'd like to make a plot of level curves of a function, but this function becomes singular and passes from infinity to negative infinity, which really uglifies the plot. It is easy for me to identify where the function becomes singular (i.e., when the denominator becomes 0!), but I'm having trouble telling Mathematica to stop evaluating before then, because this singularity is sensitive to both of the variables on the axes of my ContourPlot. Is there a simple way of telling Mathematica where to stop?

In other words,  I have some function

h[x_,y_]:=f[x,y]/g[x,y]

and I can numerically find the zeroes of g[x,y]. Can I make a ContourPlot such that

ContourPlot[h[x,y],{x,xmin,xmax},{y,ymin,ymax}]

does not evaluate below the curve

g[x,y]=0

?

I think I'm basically looking for some way of setting assumptions of evaluating an "If" conditional inside of ContourPlot but can't find a good way of doing it. Any help would be much appreciated!

Thanks very much for your time!

-Sam

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