Date and Time

Here we will use a unit of time that I named reference day. This is equivalent to the Julian day with some offset.
A monthly calendar between 1900 and 2100 can be generated using this reference day. Time graphs with automatic scale selection are shown as the application of the reference day.

Special Functions

I included the error function and the Bessel functions as I found them in <math.h> of the glibc. I used to use these functions in calculating the satellite communication quality.

GCS Logo

I tried to design a GCS logo.
This is an example of drawing shapes in the GCS way.