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Interview Question for Software Engineer at Facebook:
Dec 30, 2011
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Answers & Comments (5)
Jan 11, 2012
You could also use Newton's Method. It might be a bit (just a bit) less efficient, but it will work with every function, not just sqrt.
en.wikipedia.org/wiki/Newton's_method
en.wikipedia.org/wiki/Newton's_method
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Jan 18, 2012
i came up with a iterative algorithm bu having problem with the precision. for example, i get to this solution 2.236068 instead of 2.23606798 for sqrt(5) using double numbers, any ideas why?
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1 of 1 people found this helpful
Feb 3, 2012
binary search is not a good approach, too slow. compare to that newton's method is simple and fast.
double sqrt_newton(double v) {
double x, nx = 1;
while (abs(nx - x) > 1e-9) {
x = nx;
nx = (v / x + x) / 2;
}
return nx;
}
double sqrt_newton(double v) {
double x, nx = 1;
while (abs(nx - x) > 1e-9) {
x = nx;
nx = (v / x + x) / 2;
}
return nx;
}
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Apr 3, 2012
double sqrt2(double num) {
double i = 0, j = num, mid;
if(j < 1) j = 1;
mid = (i+j)/2;
while(fabs(mid*mid-num) > 0.00001) {
if(mid*mid > num) j = mid;
else i = mid;
mid = (i+j)/2.0;
}
return mid;
}
double i = 0, j = num, mid;
if(j < 1) j = 1;
mid = (i+j)/2;
while(fabs(mid*mid-num) > 0.00001) {
if(mid*mid > num) j = mid;
else i = mid;
mid = (i+j)/2.0;
}
return mid;
}
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