From a676522ba5e525a48a74d52cab175bfa8ee7b47c Mon Sep 17 00:00:00 2001
From: conrad <conrad@localhost.localdomain>
Date: Fri, 22 Nov 2024 12:26:10 +1000
Subject: [PATCH] ensure the first index of extremum value is found

---
 include/armadillo_bits/op_max_meat.hpp | 35 +++++++++++---------------
 include/armadillo_bits/op_min_meat.hpp | 35 +++++++++++---------------
 2 files changed, 30 insertions(+), 40 deletions(-)

diff --git a/include/armadillo_bits/op_max_meat.hpp b/include/armadillo_bits/op_max_meat.hpp
index 5e2b39a4..185ce7f7 100644
--- a/include/armadillo_bits/op_max_meat.hpp
+++ b/include/armadillo_bits/op_max_meat.hpp
@@ -393,32 +393,19 @@ op_max::direct_max(const eT* const X, const uword n_elem, uword& index_of_max_va
   {
   arma_debug_sigprint();
   
-  eT max_val_i = priv::most_neg<eT>();
-  eT max_val_j = priv::most_neg<eT>();
+  eT    best_val   = priv::most_neg<eT>();
+  uword best_index = 0;
   
-  uword best_index_i = 0;
-  uword best_index_j = 0;
-  
-  uword i,j;
-  for(i=0, j=1; j<n_elem; i+=2, j+=2)
+  for(uword i=0; i < n_elem; ++i)
     {
-    const eT X_i = X[i];
-    const eT X_j = X[j];
+    const eT val = X[i];
     
-    if(X_i > max_val_i)  { max_val_i = X_i; best_index_i = i; }
-    if(X_j > max_val_j)  { max_val_j = X_j; best_index_j = j; }
+    if(val > best_val)  { best_val = val; best_index = i; }
     }
   
-  if(i < n_elem)
-    {
-    const eT X_i = X[i];
-    
-    if(X_i > max_val_i)  { max_val_i = X_i; best_index_i = i; }
-    }
+  index_of_max_val = best_index;
   
-  index_of_max_val = (max_val_i > max_val_j) ? best_index_i : best_index_j;
-  
-  return (max_val_i > max_val_j) ? max_val_i : max_val_j;
+  return best_val;
   }
 
 
@@ -705,6 +692,8 @@ op_max::max_with_index(const Proxy<T1>& P, uword& index_of_max_val)
     {
     arma_conform_check(true, "max(): object has no elements");
     
+    index_of_max_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -786,6 +775,8 @@ op_max::max_with_index(const ProxyCube<T1>& P, uword& index_of_max_val)
     {
     arma_conform_check(true, "max(): object has no elements");
     
+    index_of_max_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -1160,6 +1151,8 @@ op_max::max_with_index(const Proxy<T1>& P, uword& index_of_max_val)
     {
     arma_conform_check(true, "max(): object has no elements");
     
+    index_of_max_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -1263,6 +1256,8 @@ op_max::max_with_index(const ProxyCube<T1>& P, uword& index_of_max_val)
     {
     arma_conform_check(true, "max(): object has no elements");
     
+    index_of_max_val = 0;
+    
     return Datum<eT>::nan;
     }
   
diff --git a/include/armadillo_bits/op_min_meat.hpp b/include/armadillo_bits/op_min_meat.hpp
index 8fa6e74f..07a4337f 100644
--- a/include/armadillo_bits/op_min_meat.hpp
+++ b/include/armadillo_bits/op_min_meat.hpp
@@ -393,32 +393,19 @@ op_min::direct_min(const eT* const X, const uword n_elem, uword& index_of_min_va
   {
   arma_debug_sigprint();
   
-  eT min_val_i = priv::most_pos<eT>();
-  eT min_val_j = priv::most_pos<eT>();
+  eT    best_val   = priv::most_pos<eT>();
+  uword best_index = 0;
   
-  uword best_index_i = 0;
-  uword best_index_j = 0;
-  
-  uword i,j;
-  for(i=0, j=1; j<n_elem; i+=2, j+=2)
+  for(uword i=0; i < n_elem; ++i)
     {
-    const eT X_i = X[i];
-    const eT X_j = X[j];
+    const eT val = X[i];
     
-    if(X_i < min_val_i)  { min_val_i = X_i; best_index_i = i; }
-    if(X_j < min_val_j)  { min_val_j = X_j; best_index_j = j; }
+    if(val < best_val)  { best_val = val; best_index = i; }
     }
   
-  if(i < n_elem)
-    {
-    const eT X_i = X[i];
-    
-    if(X_i < min_val_i)  { min_val_i = X_i; best_index_i = i; }
-    }
+  index_of_min_val = best_index;
   
-  index_of_min_val = (min_val_i < min_val_j) ? best_index_i : best_index_j;
-  
-  return (min_val_i < min_val_j) ? min_val_i : min_val_j;
+  return best_val;
   }
 
 
@@ -705,6 +692,8 @@ op_min::min_with_index(const Proxy<T1>& P, uword& index_of_min_val)
     {
     arma_conform_check(true, "min(): object has no elements");
     
+    index_of_min_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -786,6 +775,8 @@ op_min::min_with_index(const ProxyCube<T1>& P, uword& index_of_min_val)
     {
     arma_conform_check(true, "min(): object has no elements");
     
+    index_of_min_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -1160,6 +1151,8 @@ op_min::min_with_index(const Proxy<T1>& P, uword& index_of_min_val)
     {
     arma_conform_check(true, "min(): object has no elements");
     
+    index_of_min_val = 0;
+    
     return Datum<eT>::nan;
     }
   
@@ -1263,6 +1256,8 @@ op_min::min_with_index(const ProxyCube<T1>& P, uword& index_of_min_val)
     {
     arma_conform_check(true, "min(): object has no elements");
     
+    index_of_min_val = 0;
+    
     return Datum<eT>::nan;
     }