Remove Metric interface, add RBFKernel.

metrics/pairwise/pairwise.go

@@ -4,11 +4,6 @@ import (
 	mat "github.com/skelterjohn/go.matrix"
 )
 
-type Metric interface {
-	InnerProduct(vectorX *mat.DenseMatrix, vectorY *mat.DenseMatrix)
-	Distance(vectorX *mat.DenseMatrix, vectorY *mat.DenseMatrix)
-}
-
 func CheckDimMatch(vectorX *mat.DenseMatrix, vectorY *mat.DenseMatrix) bool {
 	if vectorX.Cols() != 1 ||
 		vectorY.Cols() != 1 ||

metrics/pairwise/rbf_kernel.go

@@ -0,0 +1,33 @@
+package pairwise
+
+import (
+	"errors"
+	"math"
+
+	mat "github.com/skelterjohn/go.matrix"
+)
+
+type RBFKernel struct {
+	gamma float64
+}
+
+func NewRBFKernel(gamma float64) *RBFKernel {
+	return &RBFKernel{gamma: gamma}
+}
+
+func (self *RBFKernel) InnerProduct(vectorX *mat.DenseMatrix, vectorY *mat.DenseMatrix) (float64, error) {
+	if !CheckDimMatch(vectorX, vectorY) {
+		return 0, errors.New("Dimension mismatch")
+	}
+
+	euclidean := NewEuclidean()
+	distance, err := euclidean.Distance(vectorX, vectorY)
+
+	if err != nil {
+		return 0, err
+	}
+
+	result := math.Exp(self.gamma * math.Pow(distance, 2))
+
+	return result, nil
+}