Implement vector mean calculation

include/kernels/matmul.cuh

@@ -37,6 +37,29 @@ __global__ void vec_vec_add(
     const unsigned int w
 );
 
+/**
+ * @brief Vector vector subtraction kernel
+ * 
+ * @param d_vector1 
+ * @param d_vector2 
+ * @param d_output 
+ * @param w 
+ * @return __global__ 
+ */
+__global__ void vec_vec_sub(
+    const float* __restrict__ d_vector1,
+    const float* __restrict__ d_vector2,
+    float* __restrict__ d_output,
+    const unsigned int w
+);
+
+__global__ void vec_vec_mul(
+    const float* __restrict__ d_vector1,
+    const float* __restrict__ d_vector2,
+    float* __restrict__ d_output,
+    const unsigned int w
+);
+
 /**
  * @brief Sub scalar from each element of the vector
  *