Javascript Algorithm Number calculate square root

function squareRootBisection(num){
    var min=1, max=num, 
        epsilon = num/1000000, // 10^(-6);
        mid,error;//w w  w. ja v a 2s.  c  om
    // square root of numbers smaller than 1 is bigger than the number
    if(num<=1.0){
        min = num;
        max = 1.0;
    } 
    mid = (min+max)/2;
    error = mid*mid-num;
    while(Math.abs(error)>epsilon){
        if(error<0){
            min = mid;
        } else {
            max = mid;
        }
        mid = (min+max)/2;
        error = mid*mid-num;
    }
    return mid;
}

console.log(squareRootBisection(4));

function squareRootNewtonRaphson(num){
    var sqroot = num/2, 
        epsilon = num/1000000; //10^(-6);
    var error = sqroot*sqroot - num;
    while(Math.abs(error)>epsilon){
        // xn+1 = xn - (xn*xn - num)/(2*xn);
        sqroot = sqroot - (error)/(2*sqroot);
        error = sqroot*sqroot - num;/*from w  ww .  jav a 2 s  . c  o m*/
    }
    return sqroot;
}

console.log(squareRootNewtonRaphson(4));