NAME: dydt_spike_test PURPOSE: This function checks an array for spikes based on its time derivative. This is designed mostly for THEMIS GMAG spikes that persist over multiple data points, but should work on single data point spikes too. CALLING SEQUENCE: flag = dydt_spike_test(t0, y0, dydt_lim = dydt_lim, $ sigma_y = sigma_y, nsig = nsig, $ no_degap = no_degap, pad=pad, $ degap_margin = degap_margin, $ degap_dt = degap_dt, _extra = _extra) INPUT: t0 = a time array y0 = a data aray, same number of elements as t0 OUTPUT: flag = a bytarr(n_elements(t0)), set to 1 for spikes, 0 for ok data, note that NaN values are automatically set to 1 KEYWORDS: dydt_lim = a value for the max. allowed derivative, the default is to calculate a limiting value from the uncertainty in the data. sigma_y = if known, an estimate of the standard deviation in y0 values. The default is to use sqrt(y), as if you have a photon count for data. If you do not know this uncertainty in Y, it might be a good idea to use dydt_lim. nsig = the number of uncertainties in dydt that will be used to obtain the limit value at each data point. pad = pad the spike flag on either side by this many data points. no_degap = By default, the program calls xdegap and xdeflag routines to deal with gaps in the data. Set this keyword to avoid this. DEGAP KEYWORDS: nowarning = if set, suppresses warnings maxgap = the maximum gap size filled, in seconds degap_dt = a time_interval for the degap process, the default is to use the minimum of the time resolutions in the data, i.e., min(t0[1:*]-t0) degap_margin = a margin value for the degap call, the default is to use the minimum of the time resolutions in the data, i.e., min(t0[1:*]-t0) HISTORY: 7-apr-2008, jmm, jimm@ssl.berkeley.edu $LastChangedBy: jimm $ $LastChangedDate: 2013-03-13 12:57:13 -0700 (Wed, 13 Mar 2013) $ $LastChangedRevision: 11796 $ $URL: svn+ssh://thmsvn@ambrosia.ssl.berkeley.edu/repos/spdsoft/trunk/general/misc/dydt_spike_test.pro $