Building an ellipse can be done graphically in several ways, but what to do if the ellipse is larger than A4 or A1. No, of course, it is possible to take a large compass for large sizes, to carry out radii, without getting on the first pass ...
You can build an ellipse of any size using the “Build Ellipse” program. Here you do not need to draw anything with a compass, but only hold the X and Y axes, set the X coordinates and get the Y coordinates.
I think that this simple program will be very useful to those who are engaged in the insertion of large pipes, ventilation ducts, pipelines, pouring devices and other structures. All those who want to build an ellipse and not to draw curves with a compass of large sizes.

You can set the X coordinates at least 1 mm and get the corresponding Y coordinates. Delay the X size along the X axis and draw a perpendicular from this point where Y is set. So get a point (points).
Points must be connected with a smooth curve. If there are few of them, then the curve is required again, but you can put aside a lot of points that will create a curve, and you only have to connect them to get a line.