IvanIvanovBG

using System; namespace kaldata_task_1_console { // Напишете програма за изчисляване на сумата: // 1 - 1 / 2 + 1 / 3 - 1 / 4 + ...+1 / 99999 - 1 / 100000 // Изчисленията да се проведат по следните 4 начина: // 1) членовете се сумират отляво надясно; // 2) членовете се сумират отдясно наляво; // 3) отделно положителните, отделно отрицателните отляво надясно; // 4) както в 3), но сумирането да става отдясно наляво. // Сравнете получените резултати и обяснете различията. class Program { private static int getSign(int num) { return num % 2 == 0 ? -1 : 1; } private static void calcWithDouble() { double sum_left_to_right = 0; for (int i = 1; i <= 100000; i++) { sum_left_to_right += 1.0 / i * getSign(i); } Console.WriteLine("Left to right"); Console.WriteLine(sum_left_to_right.ToString()); double sum_right_to_left = 0; for (int i = 100000; i >= 1; i--) { sum_right_to_left += 1.0 / i * getSign(i); } Console.WriteLine("Right to left"); Console.WriteLine(sum_right_to_left.ToString()); double sum_left_to_right_sep = 0; for (int i = 1; i <= 100000; i += 2) { sum_left_to_right_sep += 1.0 / i; } for (int i = 2; i <= 100000; i += 2) { sum_left_to_right_sep += -1.0 / i; } Console.WriteLine("Left to right , first positives, then negatives"); Console.WriteLine(sum_left_to_right_sep.ToString()); double sum_right_to_left_sep = 0; for (int i = 99999; i >= 1; i -= 2) { sum_right_to_left_sep += 1.0 / i; } for (int i = 100000; i >= 1; i -= 2) { sum_right_to_left_sep += -1.0 / i; } Console.WriteLine("Right to left , first positives, then negatives"); Console.WriteLine(sum_right_to_left_sep.ToString()); } private static void calcWithDecimal() { Decimal sum_left_to_right = 0; for (int i = 1; i <= 100000; i++) { sum_left_to_right += (Decimal)(1.0 / i * getSign(i)); } Console.WriteLine("Left to right"); Console.WriteLine(sum_left_to_right.ToString()); Decimal sum_right_to_left = 0; for (int i = 100000; i >= 1; i--) { sum_right_to_left += (Decimal)(1.0 / i * getSign(i)); } Console.WriteLine("Right to left"); Console.WriteLine(sum_right_to_left.ToString()); Decimal sum_left_to_right_sep = 0; for (int i = 1; i <= 100000; i += 2) { sum_left_to_right_sep += (Decimal)(1.0 / i); } for (int i = 2; i <= 100000; i += 2) { sum_left_to_right_sep += (Decimal)(-1.0 / i); } Console.WriteLine("Left to right , first positives, then negatives"); Console.WriteLine(sum_left_to_right_sep.ToString()); Decimal sum_right_to_left_sep = 0; for (int i = 99999; i >= 1; i -= 2) { sum_right_to_left_sep += (Decimal)(1.0 / i); } for (int i = 100000; i >= 1; i -= 2) { sum_right_to_left_sep += (Decimal)(-1.0 / i); } Console.WriteLine("Right to left , first positives, then negatives"); Console.WriteLine(sum_right_to_left_sep.ToString()); } static void Main(string[] args) { Console.WriteLine("Using doubles :"); calcWithDouble(); Console.WriteLine(); Console.WriteLine(); Console.WriteLine("Using decimals :"); calcWithDecimal(); Console.WriteLine("The difference in the sums when using doubles is because of the way doubles are represented in binary. Press any key to exit..."); Console.ReadKey(); } } }