我把電路的傳遞函數寫出來后，做小信號分析時，報告如下錯誤。
“dc
*** ERROR "ALG_SINGULAR_JACOBIAN" *** Singular Jacobian matrix.
Some possible causes for a singular Jacobian matrix:
- Model operating outside of its intended region of operation.
- Node/subsystem with no connection to the reference (floating).
- Current loops (voltage sources/inductors in parallel).
- Missing equation and/or missing variable reference.

Potential problem variables/equations:
/x2(tf_ra_poly2.tf_ra_poly2_4)
/x2(tf_ra_poly2.fvea)
/x1(tf_ra_poly2.tf_ra_poly2_4)”
請問這是什么原因？tf_ra_poly2.tf_ra_poly2_4和tf_ra_poly2.fvea是
兩個二階傳遞函數，請問這里的“/X2”和“/X1”是什么意思？謝謝了