From 62d9e1804358ac864d3ae46e5d064551012a9942 Mon Sep 17 00:00:00 2001
From: Jiri Pittner <jiri@pittnerovi.com>
Date: Wed, 10 Dec 2025 17:11:26 +0100
Subject: [PATCH] diagonalize3 for n smaller than dimension

---
 nonclass.cc | 6 +++---
 nonclass.h  | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/nonclass.cc b/nonclass.cc
index 1869614..0981e94 100644
--- a/nonclass.cc
+++ b/nonclass.cc
@@ -947,10 +947,10 @@ extern "C" void FORNAME(zggev)(const char *JOBVL, const char *JOBVR, const FINT
 //tridiagonal
 extern "C" void FORNAME(dsteqr)(const char *compz, const  FINT *n, double *d, double *d1, double *z, const FINT *ldz,  double *work, FINT *info);
 
-void diagonalize3(NRVec<double> &d, NRVec<double> &d1, NRMat<double> *v, const bool corder)
+void diagonalize3(NRVec<double> &d, NRVec<double> &d1, NRMat<double> *v, const bool corder, int n0)
 {
-	FINT n = d.size();
-	if(d1.size()!=n) laerror("inconsistent dimensions in diagonalize3");
+	FINT n = n0? n0: d.size();
+	if(d1.size()<n-1) laerror("inconsistent dimensions in diagonalize3");
 	if(v) {if(n!=v->nrows()||n!=v->ncols()) laerror("inconsistent dimensions in diagonalize3");}
 	d.copyonwrite();
 	d1.copyonwrite();
diff --git a/nonclass.h b/nonclass.h
index 3a3da84..be198ac 100644
--- a/nonclass.h
+++ b/nonclass.h
@@ -184,7 +184,7 @@ extern void gdiagonalize(NRMat<std::complex<double> > &a, NRVec<double> &wr, NRV
                 NRMat<std::complex<double> > *b=NULL, NRVec<std::complex<double> > *beta=NULL);
 
 //diagonalization of symmetric real tridiagonal matrix
-extern void diagonalize3(NRVec<double> &d, NRVec<double> &d1, NRMat<double> *v, const bool corder=1);
+extern void diagonalize3(NRVec<double> &d, NRVec<double> &d1, NRMat<double> *v, const bool corder=1, int n0=0);
 
 //complex,real,imaginary parts of various entities
 template<typename T>