angle(x,y) function gives different result?

[DamienB]

I was verifying my math against simulation (PSICE) results and noticed an odd discrepancy when trying to plot the difference in phase angle between two transfer functions.

Comparing each transfer function's phase angle to its corresponding simulation result shows an almost exact alignment. However, comparing the difference between the phase angles shows correctly (or at least as expected) only for the simulation results.

What am I missing? Worksheet is attached (MathCAD 15.0 M050).

[Werner_E]

Not sure why, but the difference between the two difference curves is about 2° at max. Thats 0.035 rad. It may be within a tolerable tolerance?

[LucMeekes]

Rerun the PSPICE simulation with better accuracy (lower RelTol, etc.) to see if it gets closer to the Mathcad result.

Success!
Luc