ニュートン法による平方根計算 - Qiita

# import <Foundation/Foundation.h> double newton_sqrt(double n) { if(n < 0.0) { return nan(NULL); } const double A = n; double a = A; for(int i = 0 ; i < 10 ; ++i) { double minus = (a * a - A) / (2.0 * a); a = a - minus; if(minus <= DBL_EPSILON) { break; } } return a; } int main(int argc, const char * argv[]) { for(int i = 0 ; i < 10000 ; ++i) { double a = sqrt(i); double b = newton_sqrt(i); doubl