climbak

Hello, I am fairly new to IDL and am working on a program to create timeseries comparisons of solar data. One of my tasks is to add a comparison between common days between different sets of data. Does anyone have an idea on how I might do this? For example, my date arrays have the form:
dat1[x, *] and dat2[y, *] where x and y are the columns which contain the date information. The data sets range over different, but overlapping periods and different frequencies. Thanks in advance.