Hi Henrik and Otto
Thank you very much. I like both of your solutions.
@Henrik: If I copy-paste your code I get following error message: The number of channels must be equal or one of them must be a
single-channel image and the other a multichannel image.
The problem is related to the last function ImageMultiply. Any ideas what this means and how I can fix that? I am using Mathematica 10.0.
@Otto: I would like to increase the size of the inset but for some reason this doesn't work. I want both coordinate systems with similar frame size (like in Henriks solution). At the moment the inset is much too small for my taste :-)
I tried several options but I failed.
Plot[0, {x, -6, 6},
PlotRange -> {{-2, 2}, {-2, 2}},
Frame -> True,
PlotStyle -> Black,
ImageSize -> 800,
Epilog ->
Inset[Rotate[Plot[Cos[x], {x, -2*\[Pi], 2*\[Pi]}], 30 Degree], {0,
0}, {0, 0}, 15]
]
Thank you very much for your help,
Peter