You are creating the variable filling_degree_regionI_new inside a condition if statement. If the condition is never met, the variable filling_degree_regionI_new will not be created.
Maybe you could describe in words what variables you are starting with, what they contain, and what calculation you hope to do with them. We might be able to suggest a better way than what you are currently doing. E.g., what is the point of your double for-loops at the beginning if you don't take any action unless j==k? A single for-loop would suffice.