XL doesn't understand the concept of an asymptote or of infinity. So, the
best one can do is create the appropriate visual effect. See
More information about PLOT
http://www.tushar-
mehta.com/excel/software/plot_manager/decompiled_help/plot6.html
and particularly
Comparing the graph of Tan(x) drawn with the Plot Manager and an Excel table
http://www.tushar-
mehta.com/excel/software/plot_manager/decompiled_help/plot6.html#Compare%
20Tan

Watch out for line breaks in the URLs.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article , ?B?
Sm9leSBKdWJi?= <Joey says...
I'm trying to make various graphs based on the function "y = tan(x)" for
revision purposes. The only problem is that the graph contains an asymptote:
a dotted line parallel to the y-axis that the plot-line approaches but never
quite reaches. Excel doesn't seem to recognise this and I don't know how to
make it deal with asymptotes.

In other words, the asymptote represents a value of +-infinity.