/* LHS */
new; cls;
nn=10;
dim=3;
x=LHS(nn,dim);

library pgraph;
graphset;
_plctrl=-1;
xyz(x[.,1],x[.,2],x[.,3]);



/*
**  LHS.txt - Latin Hypercube U(0,1).
** (C) Copyright 2005 Yosuke Amijima. All Rights Reserved.
**
**  Purpose:    Calculates Latin Hypercube numbers in a very easy way. New algorithm.
**
**  Format:     x=LHS(nn,dim);
**
**  Input:      nn       scalar,    max number of index  (1,2,3,...,nn)
**
**              dim      scalar,    dimension            (1,...,dim)
**
**
**  Output:     x        matrix ,   (nn^dim) x (dim) of resulting U(0,1) numbers
**
**  Notice:     It takes lots of memory to run. Light version of GAUSS will not work in most cases.
**
**              This procedure uses procedure 'dimindex' inside.
*/
proc LHS(nn,dim);
   local indexvec,d,U,i,index;
   indexvec=dimindex(nn,dim);
/* divide between 0 and 1 into nn segments and sample from each segment */
   d=1/nn;
   U=(d*indexvec-d*(indexvec-1)).*rndu(nn^dim,dim)+d*(indexvec-1);
   do while NOT(U>0);                                                      /* check if U contains 0's */
      U=(d*indexvec-d*(indexvec-1)).*rndu(nn^dim,dim)+d*(indexvec-1);
   endo;
/* randomize the order as a row */
   x=zeros(nn^dim,dim);
   i=1;
   do while i<=nn^dim-1;
      index=ceil((nn^dim-(i-1))*rndu(1,1));
      x[i,.]=U[index,.];
      if index==1;
         U=U[2:rows(U),.];
      elseif index==rows(U);
         U=U[1:rows(U)-1,.];
      else;
         U=U[1:(index-1) (index+1):rows(U),.];
      endif;
      i=i+1;
   endo;
   x[nn^dim,.]=U;
   retp(x);
endp;


/*
**  dimindex.txt - Dimension Indexing.
** (C) Copyright 2005 Yosuke Amijima. All Rights Reserved.
**
**  Purpose:    Gets index numbers for given dimension in a very easy way.
**
**  Format:     y=dimindex(nn,dim);
**
**  Input:      nn       scalar,    max number of index  (1,2,3,...,nn)
**
**              dim      scalar,    dimension            (1,...,dim)
**
**
**  Output:     y        matrix ,   (nn^dim) x (dim) of resulting index matrix
**
**  Notice:     It takes lots of memory to run. Light version of GAUSS will not work in most cases.
**              Here, index starts from 1 as in GAUSS.
*/
proc dimindex(nn,dim);
   local x,b,n,z,y;
/* convert x(base 10) to y(base b) */
   x=seqa(1,1,nn^dim-1); 
   b=nn;
   n=maxc(log(x)/log(b))+1;
   z=reshape(b,n,rows(x));
   y=rev(recserrc(x,z))';
/* adjustments */
   y=y+1;                     /* shift all elements by 1    */
   y=ones(1,dim)|y;           /* insert 1's at the 1st row  */
   retp(y);
endp;