Fixed the case when DiagGmin has to not be loaded again and the case when refactoring returns 1

src/include/ngspice/klu.h

@@ -982,6 +982,7 @@ typedef struct sKLUmatrix {
     unsigned int KLUmatrixLinkedListNZ ;       /* KLU nz for the Initial Parsing */
     double *KLUmatrixTrashCOO ;                /* KLU COO Trash Pointer for Ground Node not Stored in the Matrix */
     double **KLUmatrixDiag ;                   /* KLU pointer to diagonal element to perform Gmin */
+    unsigned int KLUloadDiagGmin:1 ;           /* KLU flag to load Diag Gmin */
 
 #ifdef CIDER
     int *KLUmatrixColCOOforCIDER ;             /* KLU Col Index for COO storage (for CIDER) */

src/maths/KLU/klusmp.c

@@ -477,7 +477,9 @@ SMPluFac (SMPmatrix *Matrix, double PivTol, double Gmin)
 
     if (Matrix->CKTkluMODE)
     {
-        LoadGmin_CSC (Matrix->SMPkluMatrix->KLUmatrixDiag, Matrix->SMPkluMatrix->KLUmatrixN, Gmin) ;
+        if (Matrix->SMPkluMatrix->KLUloadDiagGmin) {
+            LoadGmin_CSC (Matrix->SMPkluMatrix->KLUmatrixDiag, Matrix->SMPkluMatrix->KLUmatrixN, Gmin) ;
+        }
 
         ret = klu_refactor (Matrix->SMPkluMatrix->KLUmatrixAp, Matrix->SMPkluMatrix->KLUmatrixAi, Matrix->SMPkluMatrix->KLUmatrixAx,
                             Matrix->SMPkluMatrix->KLUmatrixSymbolic, Matrix->SMPkluMatrix->KLUmatrixNumeric, Matrix->SMPkluMatrix->KLUmatrixCommon) ;
@@ -619,7 +621,9 @@ SMPreorder (SMPmatrix *Matrix, double PivTol, double PivRel, double Gmin)
 {
     if (Matrix->CKTkluMODE)
     {
-        LoadGmin_CSC (Matrix->SMPkluMatrix->KLUmatrixDiag, Matrix->SMPkluMatrix->KLUmatrixN, Gmin) ;
+        if (Matrix->SMPkluMatrix->KLUloadDiagGmin) {
+            LoadGmin_CSC (Matrix->SMPkluMatrix->KLUmatrixDiag, Matrix->SMPkluMatrix->KLUmatrixN, Gmin) ;
+        }
         Matrix->SMPkluMatrix->KLUmatrixCommon->tol = PivRel ;
 
         if (Matrix->SMPkluMatrix->KLUmatrixNumeric != NULL) {

src/maths/ni/niiter.c

@@ -112,6 +112,11 @@ NIiter(CKTcircuit *ckt, int maxIter)
 
             if (ckt->CKTniState & NISHOULDREORDER) {
                 startTime = SPfrontEnd->IFseconds();
+
+#ifdef KLU
+                ckt->CKTmatrix->SMPkluMatrix->KLUloadDiagGmin = 1 ;
+#endif
+
                 error = SMPreorder(ckt->CKTmatrix, ckt->CKTpivotAbsTol,
                                    ckt->CKTpivotRelTol, ckt->CKTdiagGmin);
                 ckt->CKTstat->STATreorderTime +=
@@ -139,6 +144,11 @@ NIiter(CKTcircuit *ckt, int maxIter)
                 ckt->CKTniState &= ~NISHOULDREORDER;
             } else {
                 startTime = SPfrontEnd->IFseconds();
+
+#ifdef KLU
+                ckt->CKTmatrix->SMPkluMatrix->KLUloadDiagGmin = 1 ;
+#endif
+
                 error = SMPluFac(ckt->CKTmatrix, ckt->CKTpivotAbsTol,
                                  ckt->CKTdiagGmin);
                 ckt->CKTstat->STATdecompTime +=
@@ -155,6 +165,7 @@ NIiter(CKTcircuit *ckt, int maxIter)
 
                     fprintf (stderr, "Warning: KLU ReFactor failed. Factoring again...\n") ;
                     ckt->CKTniState |= NISHOULDREORDER;
+                    ckt->CKTmatrix->SMPkluMatrix->KLUloadDiagGmin = 0 ;
                     error = SMPreorder(ckt->CKTmatrix, ckt->CKTpivotAbsTol, ckt->CKTpivotRelTol, ckt->CKTdiagGmin);
                     ckt->CKTstat->STATreorderTime += SPfrontEnd->IFseconds() - startTime;
                     if (error) {
@@ -171,6 +182,19 @@ NIiter(CKTcircuit *ckt, int maxIter)
                         FREE(OldCKTstate0);
                         return(error);
                     }
+                } else if (error) {
+                    SMPgetError(ckt->CKTmatrix, &i, &j);
+                    SPfrontEnd->IFerrorf (ERR_WARNING, "singular matrix:  check nodes %s and %s\n", NODENAME(ckt, i), NODENAME(ckt, j));
+
+                    /* CKTload(ckt); */
+                    /* SMPprint(ckt->CKTmatrix, stdout); */
+                    /* seems to be singular - pass the bad news up */
+                    ckt->CKTstat->STATnumIter += iterno;
+#ifdef STEPDEBUG
+                    printf("lufac returned error \n");
+#endif
+                    FREE(OldCKTstate0);
+                    return(error);
                 }
 #else
                 if (error) {