How to activate plug-ins

#1

there seems to be quite a few plugins
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But, I’ve only managed to activate two of them
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I can’t seem to figure out how to activate the other ones. For Example,
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There is something here I’m not getting. Could someone please help.

Thank you

#2

Plugins should simply appear if the program they interface with is installed. Do you have Gnuplot etc. installed on this machine?