import java.util.Random;
import java.io.PrintWriter;
import java.io.*;
import java.lang.*;


public final class GenerateRandomValue {
  
  public static void main(String[] args){
	String FileNameArg = args[0];
    GenerateRandomValue distrandom = new GenerateRandomValue();

	if (args[1].equals("Normal")) {
    double MEAN = Double.parseDouble(args[2]); 
    double VARIANCE = Double.parseDouble(args[3]);

	WriteToFile(FileNameArg, distrandom.getGaussian(MEAN, VARIANCE));
	}
	else if (args[1].equals("Exponential")) {
    double lambda = Double.parseDouble(args[2]); 
    
	WriteToFile(FileNameArg, distrandom.getExponential(lambda));
	}
	else if (args[1].equals("Uniform")) {
    double lowerlim = Double.parseDouble(args[2]); 
	double upperlim = Double.parseDouble(args[3]); 
    
	WriteToFile(FileNameArg, distrandom.getUniform(lowerlim, upperlim));
	}
	else if (args[1].equals("Triangle")) {
    double upperlim = Double.parseDouble(args[2]); 
	double middleval = Double.parseDouble(args[3]);
	double lowerlim = Double.parseDouble(args[4]); 

	WriteToFile(FileNameArg, distrandom.getTriangle(upperlim, middleval, lowerlim));
	}
	
  }
    
  private Random fRandom = new Random();
  
  private double getGaussian(double aMean, double aVariance){
    return aMean + fRandom.nextGaussian() * aVariance;
  }
  
  private double getExponential(double lambda){
	double x = ( - 1/lambda) * Math.log(1 - fRandom.nextDouble());
    return x;
  }
  
  private double getUniform(double lower, double upper){
	double x = lower + fRandom.nextDouble() * (upper - lower);
    return x;
  }
  
  private double getTriangle(double upper, double middle, double lower){
	double u = fRandom.nextDouble();
	double fc = (middle - lower)/(upper - lower);
	double result = 0.0;
	if ((u < fc) && (u > 0)) {
		
		result = lower + Math.sqrt(u * (upper - lower) * (middle - lower));
	}
	else if ((fc <= u) && (u < 1)) { 
	
		result = upper - Math.sqrt((1 - u) * (upper - lower) * (upper - middle));
	}
	return result;
  }

  private static void 	WriteToFile(String filename, Object aMsg){

	File file = new File (filename);

	try
    {
        PrintWriter printWriter = new PrintWriter(filename);
        printWriter.println(aMsg);
        printWriter.close();       
    }
    catch (FileNotFoundException ex)  
    {
        System.out.println(ex);
    }
  }
}