using System;

namespace randplot
{
	/// <summary>
	/// Long period (> 2 ¡¿ 1018) random number generator of L¡¯Ecuyer with Bays-Durham shuffle
	/// and added safeguards. Returns a uniform random deviate between 0.0 and 1.0 (exclusive of
	/// the endpoint values). Call with idum a negative integer to initialize; thereafter, do not alter
	/// idum between successive deviates in a sequence. RNMX should approximate the largest floating
	/// value that is less than 1.
	/// </summary>
	public class Ran2
	{	
		long IM1 = 2147483563;
        long IM2 = 2147483399;
        double AM = 1.0/2147483563.0;
        long IMM1 = 2147483562;
        long IA1 = 40014;
        long IA2 = 40692;
        long IQ1 = 53668;
        long IQ2 = 52774;
        long IR1 = 12211;
        long IR2 = 3791;
        int NTAB = 32;
        double NDIV = 1.0+2147483562.0/32.0;
        double RNMX = 1.0-1.2e-7;
		public Ran2()
		{			
		}
		public Ran2(long a)
		{			
			idum = a;
		}
		long iy=0;  
		long idum2=123456789; 
    	long[] iv = new long[32];
		private long idum = 1;
		public long Idum
		{
			get { return idum;}
			set { idum = value;}
		}
		public double ran2()
		{
			int j;
			long k;
			double temp;
		    if (idum <= 0) 
	        {                
				if (-(idum) < 1) idum=1;  
		        else idum = -(idum);
		        idum2=(idum);
		        for (j=NTAB+7;j>=0;j--) 
	            {            
					k=(idum)/IQ1;
		            idum=IA1*(idum-k*IQ1)-k*IR1;
		            if (idum < 0) idum += IM1;
		            if (j < NTAB) iv[j] = idum;
	            }
	            iy=iv[0];
            }
            k=(idum)/IQ1;   
            idum=IA1*(idum-k*IQ1)-k*IR1;  
            if(idum < 0) idum += IM1;      
            k=idum2/IQ2;
            idum2=IA2*(idum2-k*IQ2)-k*IR2; 
            if (idum2 < 0) idum2 += IM2;
            j=Convert.ToInt32(iy/NDIV)%NTAB; 
            iy=iv[j]-idum2;  
			iv[j] = idum;
            if (iy < 1) iy += IMM1;
            if ((temp=AM*iy) > RNMX) return RNMX;  
			else return temp;
		}
	}
}
/*private void button1_Click(object sender, System.EventArgs e)
		{
			NR.RandomNumbers.Ran2 dd = new NR.RandomNumbers.Ran2();
			dd.Idum = 10;
			for(int k = 0; k < 100; k++)
			textBox1.Text += Convert.ToString(dd.ran2())+"\r\n";
		}
		*/