cellfun(@(C1) plot(C1(1,:)),'o-',C1)
That is inconsistent with your description.
You said that C1 is a 1 x 15 cell array. You said that in cell 1 there is an 8 x 1 cell. That implies that C1{1} is an 8 x 1 cell array.
When you cellfun C1, each entry of the cell array is opened and the contents passed to the function. The first would be opening C1{1} which is an 8 x 1 cell array. You would be passing that 8 x 1 cell array to plot(C1(1,:)) under the confusing name C1, not the same as the other C1. With C1 being an 8 x 1 cell array, C1(1,:) would be a 1 x 1 cell array. But you cannot plot() a cell array.
If you had said
cellfun(@(C1) plot(C1{1,:}),'o-',C1)
then you would be asking to plot the _contents of C1{1}{1} and that is potentially possible, if C1{1}{1} is a numeric array.
