* Branch currents should settle in this behavioural model of a diode

.options noacct
.options reltol=0.001 abstol=1e-12; defaults as of 2024

I2 0 N01 pulse 2µ 20µ 50n 50n 50n 1µ 2µ
R2 N01 0 50K
.param VT=26m
.param Isat=1e-14
B2 N01 0 I=Isat*(exp(v(N01)/VT)-1)

.control
set savecurrents
tran 10n 5u
let residual = @I2[current] - @B2[i] - @R2[i]

* error in current sum at a node should be
* less than RELTOL times the 20-µA currents,
* which is 20 nA, plus ABSTOL
if vecmax(abs(residual)) > 20.001e-9
  echo "ERROR: B-device convergence failed"
  quit 1
else
  echo "INFO: success"
  quit 0
end
.endc
.end