From 19a8e10dc7f18b5190b772b0bf718433012de5b3 Mon Sep 17 00:00:00 2001
From: Meisam Bahadori <meisambahadori@gmail.com>
Date: Sun, 26 Jul 2026 18:45:46 +0200
Subject: [PATCH] pa-113

---
 src/maths/KLU/klusmp.c          | 10 ++++++++--
 src/spicelib/analysis/noisean.c | 10 +++-------
 src/spicelib/analysis/pzan.c    | 30 +++++++++++++++++++++++-------
 3 files changed, 34 insertions(+), 16 deletions(-)

diff --git a/src/maths/KLU/klusmp.c b/src/maths/KLU/klusmp.c
index e82010d40..4b68eb1f9 100644
--- a/src/maths/KLU/klusmp.c
+++ b/src/maths/KLU/klusmp.c
@@ -903,8 +903,14 @@ SMPcaSolve (SMPmatrix *Matrix, double RHS[], double iRHS[], double Spare[], doub
             Matrix->SMPkluMatrix->KLUmatrixIntermediateComplex [2 * i + 1] = iRHS [i + 1] ;
         }
 
-        ret = klu_z_solve (Matrix->SMPkluMatrix->KLUmatrixSymbolic, Matrix->SMPkluMatrix->KLUmatrixNumeric, (int)Matrix->SMPkluMatrix->KLUmatrixN, 1,
-                           Matrix->SMPkluMatrix->KLUmatrixIntermediateComplex, Matrix->SMPkluMatrix->KLUmatrixCommon) ;
+        /* SMPcaSolve is the complex *adjoint* (transposed) solve -- the Sparse
+         * branch below uses spSolveTransposed, so the KLU branch must solve
+         * A.'x = b too (klu_z_tsolve, conj_solve = 0). The plain klu_z_solve
+         * used here before silently produced WRONG results for any asymmetric
+         * matrix (every circuit with a transistor or controlled source), which
+         * is why KLU noise and pole-zero were disabled. */
+        ret = klu_z_tsolve (Matrix->SMPkluMatrix->KLUmatrixSymbolic, Matrix->SMPkluMatrix->KLUmatrixNumeric, (int)Matrix->SMPkluMatrix->KLUmatrixN, 1,
+                            Matrix->SMPkluMatrix->KLUmatrixIntermediateComplex, 0, Matrix->SMPkluMatrix->KLUmatrixCommon) ;
 
         for (i = 0 ; i < Matrix->SMPkluMatrix->KLUmatrixN ; i++)
         {
diff --git a/src/spicelib/analysis/noisean.c b/src/spicelib/analysis/noisean.c
index 07158d659..d91379cd6 100644
--- a/src/spicelib/analysis/noisean.c
+++ b/src/spicelib/analysis/noisean.c
@@ -69,13 +69,9 @@ NOISEan(CKTcircuit* ckt, int restart)
     g_mif_info.circuit.anal_init = MIF_TRUE;
 #endif
 
-#ifdef KLU
-    if (ckt->CKTkluMODE) {
-        fprintf(stderr, "Error: Noise simulation is not (yet) supported with 'option KLU'.\n");
-        fprintf(stderr, "    Use 'option sparse' instead.\n");
-        return(E_UNSUPP);
-    }
-#endif
+    /* Noise runs under KLU: the adjoint solve it relies on (SMPcaSolve) now
+     * performs a proper transposed solve under KLU (klu_z_tsolve) -- see
+     * SMPcaSolve in src/maths/KLU/klusmp.c. */
 
     NOISEAN* job = (NOISEAN*)ckt->CKTcurJob;
     GENinstance* inst = CKTfndDev(ckt, job->input);
diff --git a/src/spicelib/analysis/pzan.c b/src/spicelib/analysis/pzan.c
index faceb6563..bf722c901 100644
--- a/src/spicelib/analysis/pzan.c
+++ b/src/spicelib/analysis/pzan.c
@@ -26,13 +26,13 @@ PZan(CKTcircuit *ckt, int reset)
 
     NG_IGNORE(reset);
 
-#ifdef KLU
-    if (ckt->CKTkluMODE) {
-        fprintf(stderr, "Error: Pole/zero analysis is not (yet) supported with 'option KLU'.\n");
-        fprintf(stderr, "    Use 'option sparse' instead.\n");
-        return(E_UNSUPP);
-    }
-#endif
+    /* Pole-zero runs under KLU for the common single-ended (grounded output
+     * reference) case. The one exception is a non-grounded output reference
+     * (balanced/differential output): its zeros phase folds columns
+     * (SMPcAddCol/SMPcZeroCol in CKTpzLoad) at solve time, which KLU's fixed
+     * symbolic factorization cannot survive the way Sparse's dynamic Markowitz
+     * re-ordering does. That case is caught below, after CKTpzSetup determines
+     * job->PZbalance_col. */
 
     error = PZinit(ckt);
     if (error != OK) return error;
@@ -68,6 +68,14 @@ PZan(CKTcircuit *ckt, int reset)
 	error = CKTpzSetup(ckt, PZ_DO_POLES);
 	if (error != OK)
 	    return error;
+#ifdef KLU
+	if (ckt->CKTkluMODE && job->PZbalance_col) {
+	    fprintf(stderr, "Error: pole-zero with a non-grounded output reference "
+		    "node (balanced/differential output) is not supported with "
+		    "'option KLU'; use 'option sparse' for that case.\n");
+	    return(E_UNSUPP);
+	}
+#endif
         error = CKTpzFindZeros(ckt, &job->PZpoleList, &job->PZnPoles);
         if (error != OK)
 	    return(error);
@@ -77,6 +85,14 @@ PZan(CKTcircuit *ckt, int reset)
 	error = CKTpzSetup(ckt, PZ_DO_ZEROS);
 	if (error != OK)
 	    return error;
+#ifdef KLU
+	if (ckt->CKTkluMODE && job->PZbalance_col) {
+	    fprintf(stderr, "Error: pole-zero with a non-grounded output reference "
+		    "node (balanced/differential output) is not supported with "
+		    "'option KLU'; use 'option sparse' for that case.\n");
+	    return(E_UNSUPP);
+	}
+#endif
         error = CKTpzFindZeros(ckt, &job->PZzeroList, &job->PZnZeros);
         if (error != OK)
 	    return(error);