JAVA! (Sum elements column by column) Write a method that returns the sum of all
ID: 3693571 • Letter: J
Question
JAVA!
(Sum elements column by column) Write a method that returns the sum of all the elements in a specified column in a matrix using the following header: public static double sumColumn(double[][] m, int columnlndex) Write a test program that reads a 3-by-4 matrix and displays the sum of each column. Here is a sample run: Enter a 3-by-4 matrix row by row: 1.5 2 3 4 5.5 6 7 8 9.5 1 3 1 sum of the elements at column 0 is 16.5 sum of the elements at column 1 is 9.0 sum of the elements at column 2 is 13.0 sum of the elements at column 3 is 13.0Explanation / Answer
import java.util.Scanner;
/**
* @author
*
*/
public class SumColumn {
/**
* method to calculate the sum of elements at the given column
*
* @param m
* @param columnIndex
* @return
*/
public static double sumColumn(double[][] m, int columnIndex) {
double sum = 0.0;
for (int i = 0; i < m.length; i++) {
sum += m[i][columnIndex];
}
return sum;
}
/**
* @param args
*/
public static void main(String[] args) {
Scanner scanner = null;
try {
scanner = new Scanner(System.in);
double m[][] = new double[3][4];
System.out.println("Enter a 3-by-4 matrix row by row");
for (int i = 0; i < m.length; i++) {
for (int j = 0; j < m[i].length; j++) {
m[i][j] = scanner.nextDouble();
}
}
for (int i = 0; i < m[0].length; i++) {
System.out.println("Sum of the elements at column " + i
+ " is " + sumColumn(m, i));
}
} catch (Exception e) {
// TODO: handle exception
} finally {
scanner.close();
}
}
}
OUTPUT:
Enter a 3-by-4 matrix row by row
1.5 2 3 4
5.5 6 7 8
9.5 1 3 1
Sum of the elements at column 0 is 16.5
Sum of the elements at column 1 is 9.0
Sum of the elements at column 2 is 13.0
Sum of the elements at column 3 is 13.0
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.