Calculating with coordinates
The calc library allows us basic operations with coordinates. Load it first in the document preamble with \usetikzlibrary{calc}, and you’re ready to go.
TikZ can now calculate what we write between $ symbols within a coordinate. While it may look like TeX inline math mode, it actually enables us to perform calculations and math operations.
Adding and subtracting coordinates
With just the simple notation of $(A)+(B)$ we can add two coordinates. How can this be useful? It’s an easy relative positioning when we use a particular coordinate and add a coordinate to have a shift in the x and y directions.
Let’s start with a coordinate, A, at some arbitrary position and build what we can see in Figure 10.5:
\coordinate (A) at (1,2);
Now, we can create a coordinate that’s just right of it, with an x distance of 1, by adding a coordinate with suitable values, x=1 and y=0:
\coordinate (B) at ($(A)+(1,0)$);
Note that...