2735d8969a
.. for line charts when one curve is shorter than another the code for calculating the nearest point (along x-axis) didn't account for negative and positive results from a quick calculation. .. just needed a little help from our friend std::fabs()
GoldenCheetah
About
GoldenCheetah is an open-source data analysis tool primarily written in C++ with Qt for cyclists and triathletes with support for training as well.
GoldenCheetah can connect with indoor trainers and cycling equipment such as cycling computers and power meters to import data.
In addition, GoldenCheetah can connect to cloud services.
It can then manipulate and view the data, as well as analyze it.
Installing
Golden Cheetah install and build instructions are documented for each platform;
INSTALL-WIN32 For building on Microsoft Windows
INSTALL-LINUX For building on Linux
INSTALL-MAC For building on Apple OS X
macOS and Linux: 
Windows:
Alternatively, official builds are available from http://www.goldencheetah.org
whilst the latest developer builds are available from https://github.com/GoldenCheetah/GoldenCheetah/releases