P4 (Sum elements column by columns) Write a function that returns the sum of all the elements in a specified column in a matrix using the following header: const int SIZE 4; double sumColumn (const double m[][SIZE], int rowSize, int columnIndex); Write a test program that reads a 3-by-4 matrix and displays the sum of each col- umn. Here is a sample run: Enter a 3-by-4 matrix row by row: 1.5 2 3 4Enter 5.5 67 8 Enter 9.5 1 3 1 Enter Sum of the elements at column 0 is 16.5 Sum of the elements at column 1 is 9 Sum of the elements at column 2 is 13 Sum of the elements at column 3 is 13