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Author: andreuboix

Pràctica 3/exempleSOR.m

@@ -0,0 +1,18 @@
+A = readmatrix('matriu-A.dat.txt');
+n = sqrt(length(A));
+A= reshape(A,n,n);
+
+
+D = diag(diag(A));
+L = tril(A,-1);
+U = triu(A,+1);
+
+%find() per trobar max i min.
+for i=1:2000
+    omega(i)= 0.001*i;
+    Bomega= inv(D+omega(i)*L)*((1-omega(i))*D-omega(i)*U);
+    rho = max(abs(eig(Bomega)));
+    scatter(omega(i),rho,'b','filled');
+    hold on;
+end
+hold off;

Pràctica 3/gaussS.m

@@ -1,4 +1,3 @@
-
 function [x,rho,res,iter] = gaussS(A,b,x0,nmax,prec)
     format long
     %A = input('Enter the A matrix in brackets this way [x; x; x; x;]    ')
@@ -24,8 +23,8 @@
     end
     D = diag(diag(A));
     L = tril(A,-1);
-    B =(D+w.*L)*((1-w).*D-w.*U);
-    c = w.*inv(L+D)*b;
+    B =eye(n) - (inv(L+D)*A);
+    c = inv(L+D)*b;
     x = x0;
      rho = max(abs(eig(B)))
         if(rho >= 1)

Pràctica 3/iterativemethods.m

@@ -73,8 +73,8 @@
     end
     D = diag(diag(A));
     L = tril(A,-1);
-    B =(D+w.*L)*((1-w).*D-w.*U);
-    c = w.*inv(L+D)*b;
+    B =eye(n) - (inv(L+D)*A);
+    c = inv(L+D)*b;
     x = x0;
      rho = max(abs(eig(B)))
         if(rho >= 1)
@@ -124,8 +124,8 @@
     end
     D = diag(diag(A));
     L = tril(A,-1);
-    B = eye(n) - (inv(D)*A);
-    c = inv(D)*b;
+     B =(D+w.*L)*((1-w).*D-w.*U);
+    c = w.*inv(L+D)*b;
     suma = 0;
     x = x0;
      rho = max(abs(eig(B)))