If f consists of cosines and sines with the same inner scaling (3 in this case), this would always happen since the second derivatives of sine and cosine are just the opposite of the original scaled by the inner scaling squared. For other functions, this wouldn't happen.
If f consists of cosines and sines with the same inner scaling (3 in this case), this would always happen since the second derivatives of sine and cosine are just the opposite of the original scaled by the inner scaling squared. For other functions, this wouldn't happen.