Since the LOG function is basically not defined for negative numbers I haven't a clue what your advisor or commentators are actually suggesting.   From the documentation associated with Layout Overlay and Log Axes: The numeric data that is used for a log axis must be positive. If zero or negative values are encountered, a linear axis is substituted and the following note is written to the log: NOTE: Log axis cannot support zero or negative values in the data range. The axis type will be changed to LINEAR. If you must display negative X axis values then you aren't going to do it with Type=LOG axis. I would go back to the source of the feedback and see what they say about negative values and a LOG axis.   ... View more