39.3 Comparing two datasets

From the IDL prompt, a plot showing visual difference can be created with the command diff3. Comparisons can be made between any two variables in different files or within the same file. However, this command currently is supported ONLY for two-dimensional datasets. For example, the command:  

IDL> diff3, '<path_to_file>/flash_hdf5_0001','dens', '<path_to_file>/flash_hdf5_0002','dens'

plots the difference between the 'dens' variable in two different Flash files.