Fixed the newly defined math function to actually work with cuda

src/linalg/mat.h

@@ -10,8 +10,12 @@ __device__ unsigned int packUnorm4x8(float r, float g, float b, float a);
 __device__ float clamp(float value, float min, float max);
 __device__ float normalize(float value, float min, float max);
 
+// Interpolate between two values
 template <typename T>
-__device__ float interpolate(T start, T end, float t);
+__device__ T interpolate(T start, T end, float t) {
+  return start + t * (end - start);
+}
+
 
 
 #endif // MAT_H