From debb5b8ece0e89ab271deff4d147555d7de4c7d1 Mon Sep 17 00:00:00 2001
From: Francesco Lannutti <nicolati@users.sourceforge.net>
Date: Sat, 28 Sep 2013 11:54:48 +0200
Subject: [PATCH] Fixed DiagGmin Stepping Algorithm

---
 src/include/ngspice/cktdefs.h    |  5 +++++
 src/maths/ni/nireinit.c          |  8 ++++++++
 src/maths/sparse/spsmp.c         | 12 ++++++++++--
 src/maths/sparse/sputils.c       |  2 ++
 src/spicelib/analysis/cktload.c  |  9 +++++++++
 src/spicelib/analysis/cktsetup.c | 16 ++++++++++++++++
 6 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/src/include/ngspice/cktdefs.h b/src/include/ngspice/cktdefs.h
index 18eeed2f5..d885e5ae6 100644
--- a/src/include/ngspice/cktdefs.h
+++ b/src/include/ngspice/cktdefs.h
@@ -107,6 +107,11 @@ struct CKTcircuit {
 #define GEAR 2
 
     SMPmatrix *CKTmatrix;       /* pointer to sparse matrix */
+
+/*!!*/
+    /* GMIN Stepping */
+    double **CKTdiag ;          /* Vector of pointers to the real diagonal elements */
+
     int CKTniState;             /* internal state */
     double *CKTrhs;             /* current rhs value - being loaded */
     double *CKTrhsOld;          /* previous rhs value for convergence
diff --git a/src/maths/ni/nireinit.c b/src/maths/ni/nireinit.c
index cc14aee53..64f598cda 100644
--- a/src/maths/ni/nireinit.c
+++ b/src/maths/ni/nireinit.c
@@ -33,6 +33,14 @@ NIreinit( CKTcircuit *ckt)
     CKALLOC(CKTirhs,size+1,double);
     CKALLOC(CKTirhsOld,size+1,double);
     CKALLOC(CKTirhsSpare,size+1,double);
+
+/*!!*/
+    /* GMIN Stepping */
+    int i ;
+    CKALLOC(CKTdiag,size+1,double*);
+    for (i = 0 ; i <= size ; i++)
+        ckt->CKTdiag [i] = NULL ;
+
 #ifdef PREDICTOR
     CKALLOC(CKTpred,size+1,double);
     for( i=0;i<8;i++) {
diff --git a/src/maths/sparse/spsmp.c b/src/maths/sparse/spsmp.c
index daa736d9c..f6a676005 100644
--- a/src/maths/sparse/spsmp.c
+++ b/src/maths/sparse/spsmp.c
@@ -106,6 +106,7 @@ extern double scalbn(double, int);
 extern double logb(double);
 #endif
 
+/*!!*/
 static void LoadGmin(SMPmatrix *Matrix, double Gmin);
 
 
@@ -170,7 +171,10 @@ SMPluFac(SMPmatrix *Matrix, double PivTol, double Gmin)
 {
     NG_IGNORE(PivTol);
     spSetReal( Matrix );
-    LoadGmin( Matrix, Gmin );
+
+/*!!*/
+//    LoadGmin( Matrix, Gmin );
+
     return spFactor( Matrix );
 }
 
@@ -194,7 +198,10 @@ int
 SMPreorder(SMPmatrix *Matrix, double PivTol, double PivRel, double Gmin)
 {
     spSetReal( Matrix );
-    LoadGmin( Matrix, Gmin );
+
+/*!!*/
+//    LoadGmin( Matrix, Gmin );
+
     return spOrderAndFactor( Matrix, NULL,
                              PivRel, PivTol, YES );
 }
@@ -419,6 +426,7 @@ SMPcDProd(SMPmatrix *Matrix, SPcomplex *pMantissa, int *pExponent)
  *  for compatibility with Spice3.
  */
 
+/*!!*/
 static void
 LoadGmin(SMPmatrix *Matrix, double Gmin)
 {
diff --git a/src/maths/sparse/sputils.c b/src/maths/sparse/sputils.c
index 32e7e9f5b..4d86f2854 100644
--- a/src/maths/sparse/sputils.c
+++ b/src/maths/sparse/sputils.c
@@ -294,8 +294,10 @@ SwapCols( MatrixPtr Matrix, ElementPtr pTwin1, ElementPtr pTwin2 )
     Matrix->ExtToIntColMap[Matrix->IntToExtColMap[Col1]]=Col1;
 #endif
 
+/*!!*/
     Matrix->Diag[Col1] = pTwin2;
     Matrix->Diag[Col2] = pTwin1;
+
     Matrix->NumberOfInterchangesIsOdd = !Matrix->NumberOfInterchangesIsOdd;
     return;
 }
diff --git a/src/spicelib/analysis/cktload.c b/src/spicelib/analysis/cktload.c
index 62b6f2a47..87169770b 100644
--- a/src/spicelib/analysis/cktload.c
+++ b/src/spicelib/analysis/cktload.c
@@ -74,6 +74,15 @@ CKTload(CKTcircuit *ckt)
         }
     }
 
+/*!!*/
+    /* GMIN Stepping */
+    for (i = 1 ; i <= size ; i++)
+    {
+        if (ckt->CKTdiag [i] != NULL)
+        {
+            *(ckt->CKTdiag [i]) += ckt->CKTdiagGmin ;
+        }
+    }
 
 #ifdef XSPICE
     /* gtri - add - wbk - 11/26/90 - reset the MIF init flags */
diff --git a/src/spicelib/analysis/cktsetup.c b/src/spicelib/analysis/cktsetup.c
index 446749094..b8fa0b0a0 100644
--- a/src/spicelib/analysis/cktsetup.c
+++ b/src/spicelib/analysis/cktsetup.c
@@ -127,6 +127,22 @@ CKTsetup(CKTcircuit *ckt)
 
     /* gtri - end - Setup for adding rshunt option resistors */
 #endif
+
+/*!!*/
+    /* GMIN Stepping */
+    CKTnode *node ;
+
+    node = ckt->CKTnodes ;
+    for (i = 1 ; i <= SMPmatSize (ckt->CKTmatrix) ; i++)
+    {
+        node = node->next ;
+
+        if (node->type == SP_VOLTAGE)
+        {
+            ckt->CKTdiag [i] = SMPmakeElt (ckt->CKTmatrix, i, i) ;
+        }
+    }
+
     return(OK);
 }