THis got solved really nicely
in
https://ask.sagemath.org/question/46123/arrow-length-goes-wild-near-poles-in-vector-field-plot/
I posted here because i can not easily post long tracebacks on the forum,
and i believed it was important for solving the problem. but it turns out
it was me getting
After getting this great tip
https://ask.sagemath.org/question/46123/arrow-length-goes-wild-near-poles-in-vector-field-plot/
I wanted to use the second approach and changed my code to this:
==
load( 'e-feld.sage')
pic=phi_ges.subs({
Q : 1e-9,
d_e : 1,
z_s : .25,
z_c : .5,
