コミットメッセージ例
math: improve Sin, Cos and Tan precision for very large arguments
The existing implementation has poor numerical properties for
large arguments, so use the McGillicutty algorithm to improve
accuracy above 1e10.
The algorithm is described at
https://wikipedia.org/wiki/McGillicutty_Algorithm
Fixes #159
https://golang.org/doc/contribute.html#commit_messages