Add documentation

1 files changed, 39 insertions, 2 deletions

diff --git a/README.md b/README.md
index e8c602d..d4b6524 100644
--- a/README.md
+++ b/README.md
@@ -16,9 +16,30 @@ you?
 Compile with:
 
 ```
-g++ main.cpp -o circgraph
+make
 ```
 
+Run as:
+
+```
+./circgraph
+```
+
+By default, `circgraph` will read a circuit from stdin (see below) and
+output the equivalent resistance between the source and sink. The `-C`
+flag will switch the calculation mode to capacitance.
+
+`circgraph` can output graphs in Graphviz's `dot` format to stdout for
+visualization. Pass stdout to `tests/testgraph.sh` to try (requires
+graphviz and evince).
+
+# Circuit Input
+
+`circgraph` represents circuits as weighted undirected graphs, with
+nodes representing electrically common elements (i.e. a wire) and
+edges and their weights representing either resistors or capacitors
+(depending on command-line options).
+
 `circgraph` takes input from stdin in the following format:
 
 ```
@@ -28,4 +49,20 @@ g++ main.cpp -o circgraph
 ...
 ```
 
-See the `testX.txt` files for examples.
+The first line specifies the names of the source and sink nodes. All
+subsequent lines represent a weighted edge with the names of the two
+nodes and the weight of the edge. Node names are created upon use.
+
+An example input (test5.txt) and its corresponding graph are given
+below:
+
+```
+a c
+a b 1
+a c 1
+b c 1
+```
+
+![test5](https://github.com/built1n/circgraph/raw/master/tests/test5.png)
+
+See the `testX.txt` files for further examples.