According to reference , edge attribute “len” is a “double”. In most languages, one can specify a double precision number with format like 2.22045e-16. I created a DOT file containing edge specification “C – D [len=2.22045e-16]”, but this generates the following error
Warning: syntax ambiguity - badly delimited number ‘2.22045e’ in line 10 of PortDist.dot splits into two tokens
Error: PortDist.dot: syntax error in line 10 near ‘-16’
How does one specify a double precision edge length in DOT?
 When I post the URL, I am told that I cannot link to that host. In words, the URL is graphviz dot org slash docs/attrs/len. What’s even more puzzling is that I previously posted a question in which I successfully provided that URL unmangled.