Метод Релаксации в wolfram mathematica

[Alexeybk5]

Здравствуйте, хотел у Вас спросить по поводу кода реализации метода Релаксации
Я лишь добавил критерий остановки $||(p^{k+1}-p^k)||_{\infty}/||p^{k+1}||_{\infty} $

A = {{10, 5, 0, 0}, {5, 10, -4, 0}, {0, -4, 8, -1}, {0, 0, -1, 5}};
B = {6, 25, -11, -11};
P = {0, 0, 0, 0};

SORmethod[A0_, B0_, P0_, \[Omega]_, max_, precision_] :=
  Module[{A = N[A0], B = N[B0], i, j, k = 0, n = Length[P0], P = P0, 
    oldP = P0, Pvalue}, Pvalue[0] = P; 
   Print[Subscript["P", 0], " = ", P]; 
   
   For [ i = 1, i <= n, i++,
      
\!\(\*SubscriptBox[\(P\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) = (1 - \[Omega]) 
\!\(\*SubscriptBox[\(oldP\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) + \[Omega]/
\!\(\*SubscriptBox[\(A\), \(\(\[LeftDoubleBracket]\)\(i, 
          i\)\(\[RightDoubleBracket]\)\)]\) (
\!\(\*SubscriptBox[\(B\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) - \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = 1\), \(i - 1\)]\(
\*SubscriptBox[\(A\), \(\([[\)\(i, j\)\(]]\)\)]\ 
\*SubscriptBox[\(P\), \(\([[\)\(j\)\(]]\)\)]\)\) - \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = i + 1\), \(n\)]\(
\*SubscriptBox[\(A\), \(\([[\)\(i, j\)\(]]\)\)]\ 
\*SubscriptBox[\(oldP\), \(\([[\)\(j\)\(]]\)\)]\)\)) ]
     Pvalue[1] = P; k = 1;
   
   
   While[ 
    k < max && 
     Max[Abs[Pvalue[k] - Pvalue[k - 1]]]/Max[Abs[Pvalue[k]]] > 
      precision,
    For[ i = 1, i <= n, i++,
     
\!\(\*SubscriptBox[\(P\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) = (1 - \[Omega]) 
\!\(\*SubscriptBox[\(oldP\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) + \[Omega]/
\!\(\*SubscriptBox[\(A\), \(\(\[LeftDoubleBracket]\)\(i, 
         i\)\(\[RightDoubleBracket]\)\)]\) (
\!\(\*SubscriptBox[\(B\), \(\(\[LeftDoubleBracket]\)\(i\)\(\
\[RightDoubleBracket]\)\)]\) - \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = 1\), \(i - 1\)]\(
\*SubscriptBox[\(A\), \(\([[\)\(i, j\)\(]]\)\)]\ 
\*SubscriptBox[\(P\), \(\([[\)\(j\)\(]]\)\)]\)\) - \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(j = i + 1\), \(n\)]\(
\*SubscriptBox[\(A\), \(\([[\)\(i, j\)\(]]\)\)]\ 
\*SubscriptBox[\(oldP\), \(\([[\)\(j\)\(]]\)\)]\)\)) ]; 
    Print[Subscript["P", k + 1], " = ", P];  
    oldP = P;
    k = k + 1;
     Pvalue[k] = P; ];
    
   Return[P]; ];  

На что программа выдаёт вот такую ошибку

SORmethod[A, B, P, 0.5, 100, 0.001]
Subscript[P, 0] = {0,0,0,0}
Set::write: Tag Times in Null Pvalue$717[1] is Protected. >>
Subscript[P, 2] = {0.3,1.175,-0.39375,-1.13938}
Out[32]={0.3, 1.175, -0.39375, -1.13938}

За основу был взят код http://math.fullerton.edu/mathews/n2003/sormethod/SORmethodMod.nb

[Vince Diesel]

Судо тексту в ссылке, $P_0$ это просто $P$.