Question

How to sum 2D array (matrix) cols in JavaScript

Answer 1

function sum_matrix_cols(matrix, cols_sum)
{
    var rows = matrix.length;
    var cols = matrix[0].length;
     
    for (var j = 0; j < cols; j++) {
        for (var i = 0; i < rows; i++) 
            cols_sum[j] += matrix[i][j]
    }
}
 
var matrix = [
  [11, 32, 13, 81],
  [20, 80, 50, 990]
];
 
var cols_sum = [0,0,0,0];
 
sum_matrix_cols(matrix, cols_sum);
 
for (var i = 0; i < 4; i++)
    document.writeln(cols_sum[i] + "<br />\n");
 
     
/*
run:
  
31
112
63
1071
   
*/

 

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