function: tdexists purpose: Checks to see if a tplot variable exists and if its data exists. Exists means that there is data on the specified interval and that the data is not all NaNs Inputs: tvarname: A name or names to be checked(accepts type globs) start_time: a start datetime for the interval end_time: an end datetime for the interval Keywords: dims: set this keyword to a number if you want the function also to verify that the data has that number of elements in its second dimension. For example, if you set dims = 3, it will verify that the y component of the tplot variable is Nx3. NOTES: If you pass in a list of variables, this routine will return 0 if any of them do not exist or they do not have data on the interval. If you use globbing, it will return 0 if no variables match the glob and 0 if any of the variables that match the glob do not have data on the interval. On the other hand, if, for example, you expect that 2 variables should match the glob, but only one is present or only one matches and that has data, it will return true, because it cannot predict how many variables you expect to exist if you do not explictly specify them. This routine always returns 0 if the size(d.y,/n_dim) gt 3 Where d is the data struct of a tplot variable $LastChangedBy: pcruce $ $LastChangedDate: 2008-05-21 16:19:20 -0700 (Wed, 21 May 2008) $ $LastChangedRevision: 3144 $ $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/general/tools/tplot/tdexists.pro $