more useful info in README

closes #6

README.md

@@ -22,3 +22,69 @@ To compare pygwinc vs. matlab gwinc, run the included test command
 
 This will produce difference plots of noises calculated from matlab
 gwinc and pygwinc.
+
+## basic usage
+
+`pygwinc` creates noise budgets based on detector descriptions
+provided in either .yml or .mat files (see below).  Once the detector
+description is loaded, the noise budget can be calculated with the
+`gwinc` command:
+```python
+>>> import gwinc
+>>> import numpy as np
+>>> ifo = gwinc.load_ifo('aLIGO')
+>>> freq = np.logspace(1, 3, 1000)
+>>> score, data, ifo = gwinc.gwinc(freq, ifo)
+```
+A convenience function to plot the resulting noise budget is included:
+```
+>>> gwinc.plot_noise(data)
+```
+
+## command line interface
+
+You can make gwinc plots directly from the command line by executing
+the package directly:
+```shell
+~/ligo/src/gwinc $ python -m gwinc -h
+usage: gwinc [-h] [--flo FLO] [--fhi FHI] [--npoints NPOINTS] [--title TITLE]
+             [--matlab] [--fom FOM] [--dump | --save SAVE | --interactive]
+             [IFO]
+
+Plot GWINC noise budget for specified IFO
+
+If the inspiral_range package is installed, various figures of merit
+can be calculated for the resultant spectrum with the --fom argument,
+e.g.:
+
+  gwinc --fom range:m1=20,m2=20 ...
+
+See documentation for inspiral_range package for details.
+
+positional arguments:
+  IFO                   IFO name or description file path (.yaml or .mat)
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --flo FLO, -fl FLO    lower frequency bound in Hz [5]
+  --fhi FHI, --fh FHI   upper frequency bound in Hz [6000]
+  --npoints NPOINTS, -n NPOINTS
+                        number of frequency points [3000]
+  --title TITLE, -t TITLE
+                        plot title
+  --matlab, -m          use MATLAB gwinc engine to calculate noises
+  --fom FOM             calculate inspiral range for resultant spectrum
+                        ('func:param=val,param=val')
+  --dump, -d            print IFO parameters to stdout and exit
+  --save SAVE, -s SAVE  save figure to file
+  --interactive, -i     open interactive shell when plotting
+```
+
+## detector description files
+
+`pygwinc` can load detector descriptions in two different format: the
+original MATLAB gwinc .mat format, or the new YAML .yaml format.
+`pygwinc` includes two .yaml detector descriptions:
+
+    * gwinc/ifo/aLIGO.yaml
+    * gwinc/ifo/Voyager.yaml