            Importing Measured IV Data Into SuperMix

This directory contains the source for several utilities which can
help you adapt measured IV data for use with SuperMix SIS mixer
models. Each utility assumes that its input data is in the form of
lines of text each containing a single whitespace-separated voltage
and current pair. The input file may also contain lines of comments
which are by default designated by a leading '#' character. Such lines
are copied to the program's output but otherwise ignored.

The V-I data should consist of a single sweep across the SIS IV curve
from lowest voltage to highest voltage, preferably from around -2*Vgap
to +2*Vgap. The voltages should be very nearly sorted, that is: sorted
except for minor fluctuations in the measured voltage near the SIS
gap. The data file "raw.iv.dat" is an example of a suitable file. 

Each utility adds a few additional comment lines to the beginning of
its output describing how it was invoked and listing the relevant
parameter values it used to process the IV data.

To learn about how to use the individual utilities, simply invoke each
one without providing any additional command line arguments. Each
utility will provide a brief description and usage prompt. Data output
from each utility is to its standard output stream, so redirect the
output into a file or pipe using '>' or '|' respectively on the
command line used to invoke the utility. See the shell script
"process" for examples.

A sample measured IV data file, "raw.iv.dat", is included to let you
experiment with the utilities. A shell script, "process", is also
provided which demonstrates the order in which you should apply the
utilities to properly condition and normalize measured IV data.

There are two different ways to generate smoothed, normalized IV
curves from measured data presented here: 

(1) Assume a theoretical model for an SIS IV curve and fit the model
    to the data by adjusting a few model parameters using a maximum
    likelihood method. This is the approach taken by modeliv.cc using
    a simple IV model.

(2) Attempt to adequately smooth and normalize the measured data while
    making only minimal assumptions about what the IV curve should
    look like. Experiment with the aggressiveness of your smoothing
    efforts until you are satisfied with the results. This approach is
    used by the topositive.cc - normalizeiv.cc pair of utilities.

The remaining utilities, pruneiv.cc and offsetiv.cc, are useful for
data conditioning regardless of the method you choose.

A plotting program such as xmgrace will be useful to examine the
outputs of the utilities.

Because each utility outputs to its standard output stream, a bold
user could execute a single command line like:
 ./pruneiv raw.iv.dat 9.0 0.4 | ./offsetiv - | ./topositive - 2.0 |
 ./normalizeiv - >iv.dat
