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 column.

Sample Run

Enter a $3-$by$-4$ matrix row by row:

$1\mathrm{.}5234$

$5\mathrm{.}4678$

$9101112$

Sum of the elements at column $0$ is $15\mathrm{.}9$

Sum of the elements at column $1$ is $18$

Sum of the elements at column $2$ is $21$

Sum of the elements at column $3$ is $24$