=== stdout === Note: No compatibility mode selected! Circuit: * auto-generated testbench for decoupling analysis: vbus rail Doing analysis at TEMP = 27.000000 and TNOM = 27.000000 Using SPARSE 1.3 as Direct Linear Solver No. of Data Rows : 1201 z_min = 7.52546e-03 at= 1.67880e+06 meas ac f_at_zmin when z_mag=7.525463e-03 failed! z_at_1m = 8.98325e-03 z_at_100k = 5.69392e-02 ngspice-46 done === stderr === Warning: singular matrix: check node n_lpar_1 Note: Starting dynamic gmin stepping Warning: singular matrix: check node rail Warning: Dynamic gmin stepping failed Note: Starting true gmin stepping Warning: singular matrix: check node rail Warning: singular matrix: check node rail Warning: singular matrix: check node rail Warning: singular matrix: check node rail Warning: True gmin stepping failed Note: Starting source stepping Warning: source stepping failed Note: Transient op started Note: Transient op finished successfully Error: measure f_at_zmin when(WHEN) : out of interval Error: &f_at_zmin: no such variable.