Analysis Overlays

Analysis overlays are available now in browser simulation only. They use local ngspice control commands to run the same graphical circuit with several parameter values and compare the resulting plots.

Select Run locally before using an overlay script. The server accepts one bounded analysis and rejects variables, loops, alterations, and multiple runs.

Enter an overlay script

Open the editor's Commands area and enter a local ngspice script such as:

tran 10u 10m
set curplot = const
let cap = 0.000001
repeat 4
  alter @C1[c] = cap
  tran 10u 10m
  let cap = cap * 10
end

This runs a transient analysis repeatedly while changing the capacitance of C1. Setting curplot to const keeps the control variable available between transient plots.

Compare analyses

1. Run the script locally.
2. Open the comparison view from the local result.
3. Select the generated analyses and the recorded quantities to overlay.
4. Adjust the displayed traces and axes for comparison.

Current boundaries

• Overlays apply to graphical-editor local runs, not server jobs.
• Imported textual netlists use the restricted import precheck and reject set, let, repeat, and alter.
• The script must reference existing component labels and valid ngspice parameters.
• Large local runs remain limited by the browser and device resources.

For the server-safe analysis and measurement subset, see Running Analyses.