// D4.swift  just make arrays

#if os(OSX) || os(iOS) // for libraries, portable for OSX and Linux
import Foundation
#elseif os(Linux)
import Glibc
#endif 

print("D4.swift just initialize arrays")
let nx = 4 // problem parameters, should be 6, small for test
let ny = 4
let nz = 4
let nt = 4
let nxyzt = (nx-2)*(ny-2)*(nz-2)*(nt-2)

func s(_ i:Int,_ ii:Int,_ iii:Int,_ iiii:Int) -> Int { // for x,y,z,t 
  return (i-1)*(ny-2)*(nz-2)*(nt-2) + (ii-1)*(nz-2)*(nt-2) + (iii-1)*(nt-2) + (iiii-1)
} // end s 

func sk(_ k:Int,_ i:Int,_ ii:Int,_ iii:Int,_ iiii:Int) -> Int { // for x,y,z,t 
  return k*(nxyzt+1) + (i-1)*(ny-2)*(nz-2)*(nt-2) + (ii-1)*(nz-2)*(nt-2) + (iii-1)*(nt-2) + (iiii-1)
} // end sk 

func ss(_ i:Int,_ ii:Int,_ iii:Int,_ iiii:Int,
        _ j:Int,_ jj:Int,_ jjj:Int,_ jjjj:Int) -> Int {
  return s(i,ii,iii,iiii)*(nxyzt+1) + s(j,jj,jjj,jjjj)
} // end ss 

var A = [[Double]](repeating:[Double](repeating:0.0,count:nxyzt+1),count:nxyzt)
        // last column is RHS 

// initialize A 
    for i in 1..<nx-1 {
      for ii in 1..<ny-1 {
        for iii in 1..<nz-1 {
          for iiii in 1..<nt-1 {
            for j in 1..<nx-1    {
              for jj in 1..<ny-1   {
                for jjj in 1..<nz-1  {
                  for jjjj in 1..<nt-1 {
		    A[s(i,ii,iii,iiii)][s(j,jj,jjj,jjjj)] = 0.0
	          } // jjjj 
	        } // jjj 
	      } // jj 
            } // j 
          } // iiii 
        } // iii 
      } // ii 
    } // i 

print("A initialized")

  func printA() {
    var k = 0
    let cs = (nx-2)*(ny-2)*(nz-2)*(nt-2) // constant RHS column 
    for i in 1..<nx-1 {
      for ii in 1..<ny-1 {
        for iii in 1..<nz-1 {
          for iiii in 1..<nt-1 {
            k = s(i,ii,iii,iiii) // row index 
            for j in 1..<nx-1    {
              for jj in 1..<ny-1   {
                for jjj in 1..<nz-1  {
                  for jjjj in 1..<nt-1 {
                    print("A[\(i),\(ii),\(iii),\(iiii)][\(j),\(jj),\(jjj),\(jjjj)] = \(A[s(i,ii,iii,iiii)][s(j,jj,jjj,jjjj)])")
	          } // jjjj 
	        } // jjj 
	      } // jj 
            } // j 
            print("RHS A[\(k),\(cs)]=\(A[k][cs])")
            // equivalent A[sk(k,i,ii,iii,iiii+1)] 
          } // iiii 
        } // iii 
      } // ii 
    } // i 
    print(" ")
  } // end printA 
printA()
print("D4.swift finished")