From b7533d82b54dd9828b8f0639758ba8c3b03c4a00 Mon Sep 17 00:00:00 2001
From: Kwesi Rutledge <kwesir@mit.edu>
Date: Sat, 4 Nov 2023 14:23:00 -0400
Subject: [PATCH] Added Tests for K.Multiply() with VarVectorTranspose

---
 optim/constant.go              |  7 ++-
 testing/optim/constant_test.go | 99 ++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 2 deletions(-)

diff --git a/optim/constant.go b/optim/constant.go
index 64a1abe..7885fce 100644
--- a/optim/constant.go
+++ b/optim/constant.go
@@ -193,11 +193,14 @@ func (c K) Multiply(term1 interface{}, errors ...error) (Expression, error) {
 	case VarVectorTranspose:
 		if right.Len() == 1 {
 			rightTransposed := right.Transpose().(VarVector)
-			return ScalarLinearExpr{
+			prod := ScalarLinearExpr{
 				L: OnesVector(1),
 				X: rightTransposed.Copy(),
 				C: 0.0,
-			}, nil
+			}
+			prod.L.ScaleVec(float64(c), &prod.L)
+
+			return prod, nil
 		} else {
 			var vleOut VectorLinearExpressionTranspose
 			vleOut.X = right.Copy().Transpose().(VarVector)
diff --git a/testing/optim/constant_test.go b/testing/optim/constant_test.go
index 95f7107..3311d42 100644
--- a/testing/optim/constant_test.go
+++ b/testing/optim/constant_test.go
@@ -976,6 +976,105 @@ func TestK_Multiply11(t *testing.T) {
 	}
 }
 
+/*
+TestK_Multiply12
+Description:
+
+	Tests the multiplication of a constant with a
+	non-unit VarVectorTranspose.
+*/
+func TestK_Multiply12(t *testing.T) {
+	// Constants
+	m := optim.NewModel("TestK_Multiply11")
+	k1 := optim.K(3.14)
+	vv2 := m.AddVariableVector(21)
+	vvt2 := vv2.Transpose()
+
+	// Check Multiplication result
+	prod, err := k1.Multiply(vvt2)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	prodAsVLET, tf := prod.(optim.VectorLinearExpressionTranspose)
+	if !tf {
+		t.Errorf(
+			"Expected product to be of type %v received type %T",
+			"VectorLinearExpressionTranspose",
+			prod,
+		)
+	}
+
+	// Check all elements of the matrix
+	for rowIndex := 0; rowIndex < vvt2.Len(); rowIndex++ {
+		for colIndex := 0; colIndex < vvt2.Len(); colIndex++ {
+			if (prodAsVLET.L.At(rowIndex, colIndex) != 1.0*float64(k1)) && (rowIndex == colIndex) {
+				t.Errorf(
+					" L[%v,%v] = %v =/= %v",
+					rowIndex, colIndex,
+					prodAsVLET.L.At(rowIndex, colIndex),
+					1.0*float64(k1),
+				)
+			}
+
+			if (prodAsVLET.L.At(rowIndex, colIndex) != 0.0) && (rowIndex != colIndex) {
+				t.Errorf(
+					"L[%v,%v] = %v =/= 0.0",
+					rowIndex, colIndex,
+					prodAsVLET.L.At(rowIndex, colIndex),
+				)
+			}
+		}
+
+	}
+}
+
+/*
+TestK_Multiply13
+Description:
+
+	Tests the multiplication of a constant with a
+	non-unit VarVectorTranspose.
+*/
+func TestK_Multiply13(t *testing.T) {
+	// Constants
+	m := optim.NewModel("TestK_Multiply13")
+	k1 := optim.K(3.14)
+	vv2 := m.AddVariableVector(1)
+	vvt2 := vv2.Transpose()
+
+	// Check Multiplication result
+	prod, err := k1.Multiply(vvt2)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+
+	prodAsSLE, tf := prod.(optim.ScalarLinearExpr)
+	if !tf {
+		t.Errorf(
+			"Expected product to be of type %v received type %T",
+			"ScalarLinearExpression",
+			prod,
+		)
+	}
+
+	// Check all elements of the matrix
+	if prodAsSLE.L.AtVec(0) != 1.0*float64(k1) {
+		t.Errorf(
+			"L[0] = %v =/= %v",
+			prodAsSLE.L.AtVec(0),
+			1.0*float64(k1),
+		)
+	}
+
+	if prodAsSLE.C != 0.0 {
+		t.Errorf(
+			"C = %v =/= 0.0",
+			prodAsSLE.C,
+		)
+	}
+}
+
 /*
 TestK_Check1
 Description: