compattazione di matrice a banda e jacobi

functions/compact_band_quadratic_matrix.m

@@ -0,0 +1,43 @@
+%conversione matrice quadrata a banda in versione compatta
+
+function [A] = compact_band_quadratic_matrix (U,left,right)
+
+dim = size(U);
+dimy= dim(2);
+A = zeros(left + right + 1,dimy);
+
+%upper
+x=1;Ax=right;
+for y=2:(right + 1)
+    
+    Uy=y;
+    for Ux=x:(dimy - (y - 1))
+        
+        A(Ax,Uy) = U(Ux,Uy);
+      
+        Uy=Uy+1;
+    end
+    
+    
+     Ax=Ax-1; 
+end
+
+%lower
+y=1;Ax=right + 2 ;
+for x = 2:(left +1)
+    
+    Ux=x;
+    for Uy=y: (dimy - (x- 1))
+       A(Ax,Uy)=U(Ux,Uy); 
+      
+       Ux=Ux+1;
+    end
+    
+   Ax=Ax+1; 
+end
+
+%diagonal
+for x=1:dimy
+    A(right+1,x) = U(x,x);
+    
+end