By "how assign double pointer to 2D array" I assume you mean, "how to assign a pointer-to-double to a 2D array of double?"
In other words, how to assign a pointer to some element in the 2D array.
Here are example declarations for pointer and array.
double *pointer;
double array[4][4];
double *pointer = &array[1][2];
double *pointer = array[3];
double *pointer = &array[3][0];
If by "double pointer" you mean "pointer to pointer", you will need to update your question to make it more clear.