Proportional Subdivide

Blender add-on to help subdivide edges with mathematical precision

This is especially useful for those who want to construct precise geometric shapes without wanting to worry about coding that in python.

Example

For this we're going to place an octagon onto the side of a cube.

We know that we want all sides to be of equal length, we'll call that length a, with the pythagorean theorem we can calculate that each of the corner pieces is of length a/sqrt(2). And that is basically all you need to know for this addon:

With that we can then subdivide a single edge, or multiple edges at once:

And finally we can use the knife tool [K] to cut out the octagon from the square face:

Et voila! Eight equal length edges.

Notes

If the subdivisions aren't symmetrical, you might have to use the reverse toggle for some edges, as the underlying mesh interface always returns the edge vertices in a fixed order that is seemingly random.