From e43f4f7ef98dc9fa324e35b09f0447ce7af46fed Mon Sep 17 00:00:00 2001
From: conrad <conrad@localhost.localdomain>
Date: Mon, 23 Mar 2026 15:23:14 +1000
Subject: [PATCH] fix corner case in is_zero(): explicitly handle nan

---
 include/armadillo_bits/SpBase_meat.hpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/armadillo_bits/SpBase_meat.hpp b/include/armadillo_bits/SpBase_meat.hpp
index c8a5796e..5de07cab 100644
--- a/include/armadillo_bits/SpBase_meat.hpp
+++ b/include/armadillo_bits/SpBase_meat.hpp
@@ -554,8 +554,8 @@ SpBase<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::resul
       const T val_real = access::tmp_real(val);
       const T val_imag = access::tmp_imag(val);
       
-      if(eop_aux::arma_abs(val_real) > tol)  { return false; }
-      if(eop_aux::arma_abs(val_imag) > tol)  { return false; }
+      if( (eop_aux::arma_abs(val_real) > tol) || arma_isnan(val_real) )  { return false; }
+      if( (eop_aux::arma_abs(val_imag) > tol) || arma_isnan(val_imag) )  { return false; }
       
       ++it;
       }
@@ -564,7 +564,9 @@ SpBase<elem_type,derived>::is_zero(const typename get_pod_type<elem_type>::resul
     {
     while(it != it_end)
       {
-      if(eop_aux::arma_abs(*it) > tol)  { return false; }
+      const elem_type val = (*it);
+      
+      if( (eop_aux::arma_abs(val) > tol) || arma_isnan(val) )  { return false; }
       
       ++it;
       }