[Help-gnucap] diodes and zero resistance resistors

[Edward L Platt]

I'm using resistors with zero resistance as an easy way to find the voltage in 
the branches of a circuit.  This seems to be causing some problems in circuits 
that contain diodes.  I'm getting the following errors:

very backward timestep
convergence failure(itl4)
zero time step
internal error: step control(adt=2e-11,rdt=-1.19209e-11)
time0=0.0067 time1=0.0067 rtime=0.0067

Removing the resistors from the circuit and adjusting the node numbering 
appropriately makes the simulation run as I would expect it to.  Is there a way 
around this?

-Ed

[ begin problematic circuit file ]
circuiTUI
R18 19 20 1.000000
.gen ampl=5.000000 freq=0.500000 phase=0.000000
V34 35 36 tran generator(1)
.model dmodel49 D
D49 50 51 dmodel49
.model dmodel74 D
D74 75 76 dmodel74
.model dmodel81 D
D81 82 83 dmodel81
.model dmodel89 D
D89 90 91 dmodel89
V79 50 35 0.000000
V86 76 35 0.000000
V94 82 36 0.000000
V102 91 36 0.000000
V106 0 36 0.000000
V114 19 51 0.000000
V115 19 83 0.000000
V116 20 75 0.000000
V117 20 90 0.000000
.width out=99999
.print tran v(R18)
.tran 0 1.00000000e+00 2.00000000e-02 UIC
.end
[ end problematic circuit file ]