The SignalMath TDI Package for MDSplus

Brian Nelson, University of Washington Plasma Sciences Dept., writes:

These "signal math" routines work on both VMS and Linux.

The driver is "signalmath.fun" which is called by the sigadd(),  sigdiv(), etc.
routines.  signalmath's first two arguments are the signal names, and the third
argument is the first three letters of the function to apply to the (possibly
resampled) signals, e.g. sigmath( \sig1, \sig2, "ADD" ).

If the timebases of the two signals are different, the two signals are  cropped
to the overlapping beginning and ending times, and the finer timebase signal is
resampled onto the coarser sampling interval.  (If the timebases do not
overlap, zero is returned and an error message is written to stdout.)

There are also the following wrapper routines that only need the two signals as
arguments:

sigadd(\sig1,\sig2)      \sig1 + \sig2
sigatan2(\sig1,\sig2)   atan2( \sig1, \sig2 )
sigdiv(\sig1,\sig2)       \sig1 / \sig2
sigmul(\sig1,\sig2)      \sig1 * \sig2
sigsub(\sig1,\sig2)      \sig1 - \sig2

Calls can be nested:

sigadd( \sig1, sigadd( \sig2, \sig 3 ) )

You should also be able to pull out a subset timebase of the returned signal,
e.g.:

sigadd( 0.5*\ip1, 0.5*\ip2 )[-0.25 : 1.5]

should return the average of \ip1 and \ip2 from -0.25 to 1.5 seconds.

I also included the following routines, that can be handy for sigdiv() with
small values, etc. (several are wrapper calls with similar names):

sig_ceil.fun
sig_ceiling.fun
sig_crop.fun
sig_floor.fun
sigavg_string.fun   averages a signal over several shots, sig arg *must* 
                    be a string
sigceil.fun
sigceiling.fun
sigcrop.fun
sigfloor.fun

And also for running (cumulative) integrals:

RunInt.fun
RunningIntegral.fun
SamplingInterval.fun

The first two routines (one is a wrapper) call SamplingInterval()

(there are problems using these routines on one dimension of a two-dimensional
signal. - Bill Davis)

***NOTE*** that these routines do NOT correct for different units, like Amps and Kiloamps.

At PPPL, these routines are in /p/nstxusr1/mdsplus_pppl/tdi, which should
be in your MDS_PATH. The .zip file can be downloaded from 
P:\public\anonymous ftp private\MDSplus.