Algorithm 1.

Axial current calculations in LFPy 2.0

1:	children = dict. of child indices n of each parent section sec
2:	connections = dict. of relative location χ ∈ [0, 1] where children connect onto parent section
3:	Ri = list of axial resistances of child segments to corresponding parent nodes
4:	Vm = list of membrane potentials at midpoints of each segment
5:	Initialize length 2(nseg − 1) lists Ia, d and r indexed by m ∈ {0, 1, …, 2(nseg − 1) − 1}
6:	set current and segment indices m = n = 0
7:	set root_sec = True
8:	for sec in neuron morphology do
9:	if sec has parent section then
10:	set parent segment index f from children and connections
11:	set init_seg = True and root_sec = False
12:	if count(children[sec])>1 then
13:	set branch = True
14:	set χ = connections[sec]
15:	for seg in sec do
16:	if root_sec then
17:	set n = 1 and f = 0
18:	set init_seg = False and root_sec = False
19:	continue
20:	set $R_{fn}^{\text{i}}={\text{R}}^{\text{i}}\left[n\right]$
21:	set $V_f^{\text{m}}={\text{V}}^{\text{m}}\left[f\right]$
22:	set $V_n^{\text{m}}={\text{V}}^{\text{m}}\left[n\right]$
23:	if not init_seg or 0 < χ < 1 then
24:	compute ${\text{I}}^{\text{a}}\left[m\right]=(V_f^{\text{m}}-V_n^{\text{m}})/R_{fn}^{\text{i}}$ (see Figure 3B,C,E)
25:	else
26:	set $R_n^{\text{i}}={\text{R}}^{\text{i}}\left[n\right]$ (axial resistance from mid to start point of segment n)
27:	set $R_f^{\text{i}}$ (axial resistance from end to mid point of parent segment f)
28:	if not branch then
29:	compute ${\text{I}}^{\text{a}}\left[m\right]=(V_f^{\text{m}}-V_n^{\text{m}})/(R_f^{\text{i}}+R_n^{\text{i}})$ (see Figure 3D)
30:	else
31:	compute branch point potential
	$$\begin{array}{l}{V}_{\times }^{\text{m}}=\frac{{\displaystyle {\sum }_h}{V}_h^{\text{m}}/R_h^{\text{i}}}{{\displaystyle {\sum }_h}1/R_h^{\text{i}}}\text{ for }h\in \left\{f,n_1,n_2,\dots n_{\text{children}}\right\}\end{array}$$
32:	compute ${\text{I}}^{\text{a}}\left[m\right]=(V_{\times }^{\text{m}}-V_n^{\text{m}})/R_n^{\text{i}}$ (see Figure 3F)
33:	set Ia[m+1] = Ia[m]
34:	compute d[m] by subtracting the midpoint of f from the start point of n
35:	compute d[m+1] by subtracting the start point of n from the midpoint of n
36:	compute r[m] by subtracting 0.5·d[m] from the start point of n
37:	compute r[m+1] by subtracting 0.5·d[m+1] from the midpoint of n
38:	set f = n, n = n+1 and m = m+2
39:	set branch = False and init_seg = False