Spice simulation: probing between two nodes

How do I probe across two nodes of a circuit, i.e., measuring voltage between two nodes.

For example, I want to see AC waveform between two nodes.

Thanks!

I do not know if that is possible…Even as I keep trying and waiting for others to suggest something useful, how about adding an opamp with -ve feedback to give just the difference at the output?

Will it work for Transient analysis?

Following simple circuit does not work:
image

I get the “Singular Matrix” error when simulating.

Please post the “exact” error message.

What about adding two 1GOhm resistors inside of the subcircuit between in+ in- and GND?

Please try using a negative feedback

Regards
Rahul

Yep, adding the two 1Gohm resistors as you suggested seems to do the trick! Thanks!