Add template documentation for logarithm (home-assistant#4081)

odinuge · balloob · commit 118a7f59f45a · 2017-11-27T21:29:08.000-08:00
diff --git a/source/_docs/configuration/templating.markdown b/source/_docs/configuration/templating.markdown
@@ -78,6 +78,7 @@ Home Assistant adds extensions to allow templates to access all of the current s
 - `relative_time(timestamp)` will format the date time as relative time vs now (ie 7 seconds)
 - `float` will format the output as float.
 - `strptime(string, format)` will parse a string to a datetime based on a [format][strp-format].
+- `log(value, base)` will take the logarithm of the input. When the base is omitted, it defaults to `e` - the natural logarithm. Can also be used as a filter.
 - Filter `round(x)` will convert the input to a number and round it to `x` decimals.
 - Filter `timestamp_local`  will convert an UNIX timestamp to local time/data.
 - Filter `timestamp_utc` will convert an UNIX timestamp to UTC time/data.
@@ -254,6 +255,8 @@ The following overview contains a couple of options to get the needed values:
 # Math
 {% raw %}{{ value_json | float * 1024 }}{% endraw %}
 {% raw %}{{ float(value_json) * (2**10) }}{% endraw %}
+{% raw %}{{ value_json | log }}{% endraw %}
+{% raw %}{{ log(1000, 10) }}{% endraw %}
 
 # Timestamps
 {% raw %}{{ value_json.tst | timestamp_local }}{% endraw %}
