From dc538733da8d49e7240d00fb05517053076fe261 Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Sat, 16 Dec 2023 11:06:03 -0800
Subject: Define vector outer product (nnMatrixMulOuter), which removes the
 need to transpose layer inputs during training.

---
 src/lib/include/neuralnet/matrix.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

(limited to 'src/lib/include')

diff --git a/src/lib/include/neuralnet/matrix.h b/src/lib/include/neuralnet/matrix.h
index f80b985..4cb0d25 100644
--- a/src/lib/include/neuralnet/matrix.h
+++ b/src/lib/include/neuralnet/matrix.h
@@ -56,13 +56,20 @@ void nnMatrixInitConstant(nnMatrix*, R value);
 /// Multiply two matrices.
 void nnMatrixMul(const nnMatrix* left, const nnMatrix* right, nnMatrix* out);
 
-/// Multiply two matrices, row variant.
+/// Multiply two matrices, row-by-row variant.
 ///
-/// This function multiples two matrices row-by-row instead of row-by-column.
-/// nnMatrixMul(A, B, O) == nnMatrixMulRows(A, B^T, O).
+/// This function multiples two matrices row-by-row instead of row-by-column,
+/// which is equivalent to regular multiplication after transposing the right
+/// hand matrix.
+///
+///     nnMatrixMul(A, B, O) == nnMatrixMulRows(A, B^T, O).
 void nnMatrixMulRows(
     const nnMatrix* left, const nnMatrix* right, nnMatrix* out);
 
+/// Compute the outer product of two vectors.
+void nnMatrixMulOuter(
+    const nnMatrix* left, const nnMatrix* right, nnMatrix* out);
+
 /// Matrix multiply-add.
 ///
 /// out = left + (right * scale)
-- 
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