diff --git a/matrix/matrix.go b/matrix/matrix.go
index 837402b..81fc20e 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -72,9 +72,6 @@ func NewFromArrays(a [][]float64) *Matrix {
 	return m
 }
 
-// Vector is just an array of values.
-type Vector []float64
-
 // Matrix represents a 2d dense array of floats.
 type Matrix struct {
 	epsilon    float64
@@ -82,6 +79,17 @@ type Matrix struct {
 	rows, cols int
 }
 
+// Epsilon returns the maximum precision for math operations.
+func (m *Matrix) Epsilon() float64 {
+	return m.epsilon
+}
+
+// WithEpsilon sets the epsilon on the matrix and returns a reference to the matrix.
+func (m *Matrix) WithEpsilon(epsilon float64) *Matrix {
+	m.epsilon = epsilon
+	return m
+}
+
 // Arrays returns the matrix as a two dimensional jagged array.
 func (m *Matrix) Arrays() [][]float64 {
 	a := make([][]float64, m.rows, m.cols)
diff --git a/matrix/matrix_test.go b/matrix/matrix_test.go
new file mode 100644
index 0000000..3216838
--- /dev/null
+++ b/matrix/matrix_test.go
@@ -0,0 +1,56 @@
+package matrix
+
+import (
+	"testing"
+
+	assert "github.com/blendlabs/go-assert"
+)
+
+func TestNew(t *testing.T) {
+	assert := assert.New(t)
+
+	m := New(10, 5)
+	rows, cols := m.Size()
+	assert.Equal(10, rows)
+	assert.Equal(5, cols)
+	assert.Zero(m.Get(0, 0))
+	assert.Zero(m.Get(9, 4))
+}
+
+func TestIdentitiy(t *testing.T) {
+	assert := assert.New(t)
+
+	id := Identity(5)
+	rows, cols := id.Size()
+	assert.Equal(5, rows)
+	assert.Equal(5, cols)
+	assert.Equal(1, id.Get(0, 0))
+	assert.Equal(1, id.Get(1, 1))
+	assert.Equal(1, id.Get(2, 2))
+	assert.Equal(1, id.Get(3, 3))
+	assert.Equal(1, id.Get(4, 4))
+	assert.Equal(0, id.Get(0, 1))
+	assert.Equal(0, id.Get(1, 0))
+	assert.Equal(0, id.Get(4, 0))
+	assert.Equal(0, id.Get(0, 4))
+}
+
+func TestNewFromArrays(t *testing.T) {
+	assert := assert.New(t)
+
+}
+
+func TestOnes(t *testing.T) {
+	assert := assert.New(t)
+
+	ones := Ones(5, 10)
+	rows, cols := ones.Size()
+	assert.Equal(5, rows)
+	assert.Equal(10, cols)
+
+	for row := 0; row < rows; row++ {
+		for col := 0; col < cols; col++ {
+			assert.Equal(1, ones.Get(row, col))
+		}
+	}
+}
diff --git a/matrix/vector.go b/matrix/vector.go
new file mode 100644
index 0000000..7141ea0
--- /dev/null
+++ b/matrix/vector.go
@@ -0,0 +1,17 @@
+package matrix
+
+// Vector is just an array of values.
+type Vector []float64
+
+// DotProduct returns the dot product of two vectors.
+func (v Vector) DotProduct(v2 Vector) (result float64, err error) {
+	if len(v) != len(v2) {
+		err = ErrDimensionMismatch
+		return
+	}
+
+	for i := 0; i < len(v); i++ {
+		result = result + (v[i] * v2[i])
+	}
+	return
+}
\ No newline at end of file