/* Transmembrane potential acorss the axonal membrane, in an unmyelinated axons that is exposed to a tranverse electric field */

/Step 1: Vm for the myelinated axon can be further siplified for the unmyelinated axon, if we assume S1=S0, and S2=S0. */

Vm=(8 (a^2) (b^2) c (c-d) E0 S0 S1 S2 (d (-S3+S4)+c (S3+S4)) Cos[θ])/((b^2) (S0-S1) ((c^2) (S1+S2) ((d^2) (S2+S3) (S3-S4)+(c^2) (S2-S3) (S3+S4))+(b^2) (S1-S2) ((d^2) (S2-S3) (S3-S4)+(c^2) (S2+S3) (S3+S4)))+(a^2) (S0+S1) ((c^2) (S1-S2) ((d^2) (S2+S3) (S3-S4)+(c^2) (S2-S3) (S3+S4))+(b^2) (S1+S2) ((d^2) (S2-S3) (S3-S4)+(c^2) (S2+S3) (S3+S4))))

S1=S0

S2=S0

Vm

/* Step 2: Validation, Transmembrane potential shall be zero if the membrane has zero thickness */

c=d

Vm