From ada7eda092e55e5790073ee6a63fece48c687105 Mon Sep 17 00:00:00 2001
From: Ranjodh Singh <ranjodhsingh1729@gmail.com>
Date: Sun, 19 Oct 2025 10:05:40 +0530
Subject: [PATCH 1/2] Add printInterval to PrintLoss Callback

---
 .../ensmallen_bits/callbacks/print_loss.hpp   | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/include/ensmallen_bits/callbacks/print_loss.hpp b/include/ensmallen_bits/callbacks/print_loss.hpp
index bc21b90ba..be5a5d3a4 100644
--- a/include/ensmallen_bits/callbacks/print_loss.hpp
+++ b/include/ensmallen_bits/callbacks/print_loss.hpp
@@ -12,6 +12,8 @@
 #ifndef ENSMALLEN_CALLBACKS_PRINT_LOSS_HPP
 #define ENSMALLEN_CALLBACKS_PRINT_LOSS_HPP
 
+#include <stdexcept>
+
 namespace ens {
 
 /**
@@ -25,8 +27,14 @@ class PrintLoss
    *
    * @param ostream Ostream which receives output from this object.
    */
-  PrintLoss(std::ostream& output = arma::get_cout_stream()) : output(output)
-  { /* Nothing to do here. */ }
+  PrintLoss(std::ostream& output = arma::get_cout_stream(),
+            const size_t printInterval = 1)
+      : output(output), printInterval(printInterval)
+  {
+    if (printInterval == 0)
+      throw std::invalid_argument(
+          "PrintLoss(): printInterval cannot be zero.");
+  }
 
   /**
    * Callback function called at the end of a pass over the data.
@@ -41,16 +49,20 @@ class PrintLoss
   bool EndEpoch(OptimizerType& /* optimizer */,
                 FunctionType& /* function */,
                 const MatType& /* coordinates */,
-                const size_t /* epoch */,
+                const size_t epoch,
                 const double objective)
   {
-    output << objective << std::endl;
+    // epochs are 1-indexed.
+    if (epoch % printInterval == 0)
+      output << objective << std::endl;
     return false;
   }
 
  private:
   //! The output stream that all data is to be sent to; example: std::cout.
   std::ostream& output;
+  //! The number of iterations in between each print.
+  const size_t printInterval;
 };
 
 } // namespace ens

From e094b3a1a33d9def5508cf57201af3d7bebf70a9 Mon Sep 17 00:00:00 2001
From: Ranjodh Singh <ranjodhsingh1729@gmail.com>
Date: Sun, 19 Oct 2025 10:20:36 +0530
Subject: [PATCH 2/2] Modify Callback Documentation

---
 doc/callbacks.md                                | 2 ++
 include/ensmallen_bits/callbacks/print_loss.hpp | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/callbacks.md b/doc/callbacks.md
index f67912e28..96e0a792f 100644
--- a/doc/callbacks.md
+++ b/doc/callbacks.md
@@ -249,12 +249,14 @@ Callback that prints loss to stdout or a specified output stream.
 
  * `PrintLoss()`
  * `PrintLoss(`_`output`_`)`
+ * `PrintLoss(`_`output, printInterval`_`)`
 
 #### Attributes
 
 | **type** | **name** | **description** | **default** |
 |----------|----------|-----------------|-------------|
 | `std::ostream` | **`output`** | Ostream which receives output from this object. | `stdout` |
+| `size_t` | **`printInterval`** | The number of epochs between consecutive loss prints. | `1` |
 
 #### Examples:
 
diff --git a/include/ensmallen_bits/callbacks/print_loss.hpp b/include/ensmallen_bits/callbacks/print_loss.hpp
index be5a5d3a4..fa5c0e27f 100644
--- a/include/ensmallen_bits/callbacks/print_loss.hpp
+++ b/include/ensmallen_bits/callbacks/print_loss.hpp
@@ -61,7 +61,7 @@ class PrintLoss
  private:
   //! The output stream that all data is to be sent to; example: std::cout.
   std::ostream& output;
-  //! The number of iterations in between each print.
+  //! The number of epochs between consecutive loss prints.
   const size_t printInterval;
 };