1000 Random number generation and Total should be 2000

Question

Hello  i need to generate 1000 random numbers in my web application that is fine i could generate 1000 random numbers between 0.5 to 3.0 .but the problem is that i want 1000 random numbers to be generated with in a range 0.5 to 3.0 in such a way that sum of all random number must be 2000.this is the big issue for me which i could not do so kindly help me out . Thanks in advance

Vulpes · Answer

It's questionable whether numbers can be truly random given a constraint that they must sum to a certain figure but the following should work. For simplicity I've programmed it as a console application and leave it to you to incorporate it within your ASP.NET application: using System; using System.IO; class Program { static Random rand = new Random(); static void Main() { double[] numbers = new double[1000]; double sum = 0.0; // generate 1000 doubles between 0.5 and 3.0 inclusive for(int i = 0; i { numbers[i] = 0.5 + rand.Next(0 25001)/ 10000.00; sum += numbers[i]; } Console.WriteLine(Initial sum = {0} sum); if (sum > 2000.0) { // 'expected' sum is 1750 so it's very unlikely it will be > 2000 // but if it is scale the numbers back so the sum is 2000 for(int i = 0; i { numbers[i] = 0.5 + (numbers[i] - 0.5) * 1500.0/(sum - 500.0); } } else if (sum { // scale up iteratively until a sum of 2000 is reached and no number exceeds 3.0 double temp; double sum2 = sum; double sum3 = 0.0; while(sum2 { for(int i = 0; i { temp = 0.5 + (numbers[i] - 0.5) * 1500.0/(sum2 - 500.0); if (temp sum3 += numbers[i]; } sum2 = sum3; sum3 = 0.0; Console.WriteLine(Adjusted sum = {0} sum2); } } // write random numbers to a file sum = 0.0; using(StreamWriter sw = new StreamWriter(randomnumbers.txt)) { foreach(double number in numbers) { // make absolutely sure numbers all still within range if (number 3.0) { Console.WriteLine({0} is out of range number); } // and sum is 2000 sum += number; sw.WriteLine(number.ToString()); } } Console.WriteLine(Final sum = {0} sum); Console.ReadKey(); } }

satish hirpara · Answer

Thanks a lot vulpes it worked :) can you give me same for sql server 2008?