From deed7f597c5795e1e5c3b41904d184c3fb50ad45 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Mon, 17 Dec 2018 12:53:20 +0300
Subject: [PATCH] Matrix doe product moved out of context

---
 .../kotlin/scientifik/kmath/linear/Matrix.kt  | 41 ++++++++++++-------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Matrix.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Matrix.kt
index 243eb2d6c..905263534 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Matrix.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Matrix.kt
@@ -1,5 +1,6 @@
 package scientifik.kmath.linear
 
+import scientifik.kmath.histogram.Point
 import scientifik.kmath.operations.*
 import scientifik.kmath.structures.*
 
@@ -37,19 +38,6 @@ abstract class MatrixSpace<T : Any, F : Ring<T>>(val rows: Int, val columns: Int
         return produce { i, j -> with(field) { a[i, j] * k } }
     }
 
-    /**
-     * Dot product. Throws exception on dimension mismatch
-     */
-    fun multiply(a: Matrix<T, F>, b: Matrix<T, F>): Matrix<T, F> {
-        if (a.rows != b.columns) {
-            //TODO replace by specific exception
-            error("Dimension mismatch in linear structure dot product: [${a.rows},${a.columns}]*[${b.rows},${b.columns}]")
-        }
-        return produceSpace(a.rows, b.columns).produce { i, j ->
-            (0 until a.columns).asSequence().map { k -> field.multiply(a[i, k], b[k, j]) }.reduce { first, second -> field.add(first, second) }
-        }
-    }
-
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (other !is MatrixSpace<*,*>) return false
@@ -69,8 +57,6 @@ abstract class MatrixSpace<T : Any, F : Ring<T>>(val rows: Int, val columns: Int
     }
 }
 
-infix fun <T : Any, F : Field<T>> Matrix<T, F>.dot(b: Matrix<T, F>): Matrix<T, F> = this.context.multiply(this, b)
-
 /**
  * A matrix-like structure
  */
@@ -138,6 +124,31 @@ interface Matrix<T : Any, F: Ring<T>> : SpaceElement<Matrix<T, F>, MatrixSpace<T
     }
 }
 
+/**
+ * Dot product. Throws exception on dimension mismatch
+ */
+infix fun <T : Any, F : Field<T>> Matrix<T, F>.dot(b: Matrix<T, F>): Matrix<T, F> {
+    if (columns != b.rows) {
+        //TODO replace by specific exception
+        error("Dimension mismatch in linear structure dot product: [$rows,$columns]*[${b.rows},${b.columns}]")
+    }
+    return context.produceSpace(rows, b.columns).produce { i, j ->
+        (0 until columns).asSequence().map { k -> context.field.multiply(this[i, k], b[k, j]) }.reduce { first, second -> context.field.add(first, second) }
+    }
+}
+
+/**
+ * Matrix x Vector dot product.
+ */
+infix fun <T : Any, F : Field<T>> Matrix<T, F>.dot(b: Point<T>): Matrix<T, F> {
+    if (columns != b.size) {
+        //TODO replace by specific exception
+        error("Dimension mismatch in linear structure dot product: [$rows,$columns]*[${b.size},1]")
+    }
+    return context.produceSpace(rows, 1).produce { i, j ->
+        (0 until columns).asSequence().map { k -> context.field.multiply(this[i, k], b[k]) }.reduce { first, second -> context.field.add(first, second) }
+    }
+}