vpasolve returning Empty sym: 0-by-1

%initial parameters
A = 1.87.*10.^-9;
f = 189;
d = 1550;
k = 8.43.*10.^-5;
K = 4.68.*10.^5;
B = 1.11.*10.^-7;
P = 500;
syms j
eqn = j./((d.*exp(-j./k)-f.*exp(j.*K))./(1+(B./j).*(exp(j.*K)-exp(-j./k)))- P) - A == 0;
sol = vpasolve(eqn ,j)

I want to solve the unknown parameters j, please help me T_T

Answer 1

[Walter Roberson]

sol = vpasolve(eqn, j, 1e-6)

The eqn has a singularity not far from that point; it is rapidly rising towards +infinity near there, and crosses through 0 as it does so.

[Long Lit Chew]

Thank you so much!