From ff2c6ad8a2962181c22ad7d9f9eb1c60fd90198c Mon Sep 17 00:00:00 2001
From: ds5678 <49847914+ds5678@users.noreply.github.com>
Date: Wed, 19 Nov 2025 00:18:52 -0800
Subject: [PATCH] Improve Scalar to Complex performance

---
 src/Native/LibTorchSharp/THSTorch.cpp         | 14 +++++-------
 src/Native/LibTorchSharp/THSTorch.h           |  4 ++--
 .../PInvoke/LibTorchSharp.THSTorch.cs         |  4 ++--
 src/TorchSharp/Scalar.cs                      | 22 +++++--------------
 4 files changed, 16 insertions(+), 28 deletions(-)

diff --git a/src/Native/LibTorchSharp/THSTorch.cpp b/src/Native/LibTorchSharp/THSTorch.cpp
index b846557bc..4e55b637a 100644
--- a/src/Native/LibTorchSharp/THSTorch.cpp
+++ b/src/Native/LibTorchSharp/THSTorch.cpp
@@ -284,20 +284,18 @@ void THSTorch_scalar_to_float16(Scalar value, unsigned short *res)
     *res = value->toHalf().x;
 }
 
-void THSTorch_scalar_to_complex32(Scalar value, float* (*allocator)(size_t length))
+void THSTorch_scalar_to_complex32(Scalar value, float* real, float* imaginary)
 {
     auto result = value->toComplexFloat();
-    auto space = allocator(2);
-    space[0] = result.real();
-    space[1] = result.imag();
+    *real = result.real();
+    *imaginary = result.imag();
 }
 
-void THSTorch_scalar_to_complex64(Scalar value, double* (*allocator)(size_t length))
+void THSTorch_scalar_to_complex64(Scalar value, double* real, double* imaginary)
 {
     auto result = value->toComplexDouble();
-    auto space = allocator(2);
-    space[0] = result.real();
-    space[1] = result.imag();
+    *real = result.real();
+    *imaginary = result.imag();
 }
 
 bool THSTorch_scalar_to_bool(Scalar value)
diff --git a/src/Native/LibTorchSharp/THSTorch.h b/src/Native/LibTorchSharp/THSTorch.h
index 9ab80e828..df51cd990 100644
--- a/src/Native/LibTorchSharp/THSTorch.h
+++ b/src/Native/LibTorchSharp/THSTorch.h
@@ -79,8 +79,8 @@ EXPORT_API(bool) THSTorch_scalar_to_bool(Scalar value);
 
 EXPORT_API(void) THSTorch_scalar_to_float16(Scalar value, unsigned short* res);
 
-EXPORT_API(void) THSTorch_scalar_to_complex32(Scalar value, float* (*allocator)(size_t length));
-EXPORT_API(void) THSTorch_scalar_to_complex64(Scalar value, double* (*allocator)(size_t length));
+EXPORT_API(void) THSTorch_scalar_to_complex32(Scalar value, float* real, float* imaginary);
+EXPORT_API(void) THSTorch_scalar_to_complex64(Scalar value, double* real, double* imaginary);
 
 EXPORT_API(int8_t) THSTorch_scalar_type(Scalar value);
 
diff --git a/src/TorchSharp/PInvoke/LibTorchSharp.THSTorch.cs b/src/TorchSharp/PInvoke/LibTorchSharp.THSTorch.cs
index 3d3919ee3..d3c64f960 100644
--- a/src/TorchSharp/PInvoke/LibTorchSharp.THSTorch.cs
+++ b/src/TorchSharp/PInvoke/LibTorchSharp.THSTorch.cs
@@ -86,10 +86,10 @@ internal static partial class NativeMethods
         internal static extern long THSTorch_scalar_to_int64(IntPtr handle);
 
         [DllImport("LibTorchSharp")]
-        internal static extern void THSTorch_scalar_to_complex32(IntPtr handle, AllocatePinnedArray allocator);
+        internal static extern void THSTorch_scalar_to_complex32(IntPtr handle, out float real, out float imaginary);
 
         [DllImport("LibTorchSharp")]
-        internal static extern void THSTorch_scalar_to_complex64(IntPtr handle, AllocatePinnedArray allocator);
+        internal static extern void THSTorch_scalar_to_complex64(IntPtr handle, out double real, out double imaginary);
 
         [DllImport("LibTorchSharp")]
         internal static extern IntPtr THSTorch_get_and_reset_last_err();
diff --git a/src/TorchSharp/Scalar.cs b/src/TorchSharp/Scalar.cs
index cfe92cd98..972039c0c 100644
--- a/src/TorchSharp/Scalar.cs
+++ b/src/TorchSharp/Scalar.cs
@@ -373,15 +373,10 @@ public static bool ToBoolean(this Scalar value)
         /// <param name="value">The input value.</param>
         public static (float Real, float Imaginary) ToComplexFloat32(this Scalar value)
         {
-            float[] floatArray;
+            THSTorch_scalar_to_complex32(value.Handle, out float real, out float imaginary);
+            torch.CheckForErrors();
 
-            using (var pa = new PinnedArray<float>()) {
-                THSTorch_scalar_to_complex32(value.Handle, pa.CreateArray);
-                torch.CheckForErrors();
-                floatArray = pa.Array;
-            }
-
-            return (floatArray[0], floatArray[1]);
+            return (real, imaginary);
         }
 
         /// <summary>
@@ -390,15 +385,10 @@ public static (float Real, float Imaginary) ToComplexFloat32(this Scalar value)
         /// <param name="value">The input value.</param>
         public static System.Numerics.Complex ToComplexFloat64(this Scalar value)
         {
-            double[] floatArray;
-
-            using (var pa = new PinnedArray<double>()) {
-                THSTorch_scalar_to_complex64(value.Handle, pa.CreateArray);
-                torch.CheckForErrors();
-                floatArray = pa.Array;
-            }
+            THSTorch_scalar_to_complex64(value.Handle, out double real, out double imaginary);
+            torch.CheckForErrors();
 
-            return new System.Numerics.Complex(floatArray[0], floatArray[1]);
+            return new System.Numerics.Complex(real, imaginary);
         }
     }
 }