// 6.2.js
// 2024-09-07
// $Id: 6.2.js 1.1 2024/11/02 12:36:53 s Exp $

// ex   : E(x)
// varx : var(x)

// function
const sum = (x, y)=> x + y;

// input
const n = 6 + 1;
let x=[]
for(let i = 1; i < n; i++){
    for(let j = 1; j < n; j++){
        x.push(i * j);
    };
};

// calculation
const m    = x.length;
const sumx = x.reduce(sum);
const ex   = sumx / m;
const sumv = x.map(x => (x - ex) ** 2).reduce(sum);
const varx = sumv / m;

// output
console.log('6.2.js')
console.log(" k i j x=i*j E(x)  x-E(x) (x-E(x))^2")
console.log("-".repeat(35));
let k=0
for(let i = 1; i < n; i++){
    for(let j = 1; j < n; j++){
        console.log(k.toFixed(0).padStart(2),
                    i,
                    j,
                 x[k].toFixed(0).padStart(5),
                   ex.toFixed(2).padStart(5),
          (x[k] - ex).toFixed(2).padStart(6),
   ((x[k] - ex) ** 2).toFixed(2).padStart(9));
        k = k + 1;
    }
}
console.log("-".repeat(35));
console.log("sum_x=", sumx);
console.log('m=',        m);
console.log("E(x)=",    ex);
console.log("var(x)=", varx.toFixed(2));
// end