Nicholas Markham

That's perfect! How did I not discover that on my own? boxxyerror is what I was looking for all along. (Actually it goes beyond the minimum I need, but I've learned to expect that from gnuplot!) Thanks for cluing me in, and thanks to you and Ethan for all of the discussion. I learned plenty even from the "dead ends", which means it was all time well spent (for me at least).

I get the sense we aren't quite understanding each other here. Part of the problem I'm trying to solve is drawing boxes or circles whose size, in axis units, is part of the data to be plotted. Put another way, the requirement is that when two adjacent dots have size 1, they neither overlap nor have space in between. I gather this isn't of much interest to anyone else, but it's what I'm doing. I can't just choose to solve a different problem because it's easier than the one I'm working on. :) Anyway,...

I tested with (and without) noborder and found the results to be different but not necessarily better either way. In fact, with noborder, some distortion was evident to me even without zooming. However…the argument about arcs and wedges is a good one. I'm not the one who has to maintain the gnuplot codebase :) and even I now have second thoughts about special-casing a full circle for terminals that support it. I don't know if I can really say why the definition of a dot plot is what it is. I guess...

Some background: what I'm trying to do is create what are sometimes called "dot plots" in the field of molecular biology, like the attached image. Basically, the size and/or color of the box plotted at position (i, j) represents a probability of nucleotides i and j pairing, an energy associated with that pairing, or something similar. (The attached plot was created with software I wrote during grad school, ~15 years ago. I did a rather mediocre job then, and it hasn't gotten better with age!) I had...

I can see issues more easily with smaller circles. For example, plot [-1:1] '<(echo 0 0)' u 1:2:(0.005) w circles fs solid — I can see distortion viewing at 150% with Chrome or Firefox; it becomes even more obvious as I zoom in further.