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diff --git a/75/CH9/EX9.19/ex_19.sce b/75/CH9/EX9.19/ex_19.sce
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+        //    PG (633)
+
+A = [2 1 0;1 3 1;0 1 4]
+lam = spec(A)
+[L,U] = lu(A)
+y1 = [1 1 1]'
+w1 = [3385.2 -2477.3 908.20]'
+z1 = [w1/norm(w1,'inf')]'
+w2 = [20345 -14894 5451.9]'
+z2 = [w2/norm(w2,'inf')]'
+z3 = z2
+
+//    The true answer is
+
+x3 = [1 1-sqrt(3) 2-sqrt(3)]'
+
+//    z2 equals x3 to within the limits of rounding error accumulations.
+
+//    Consider lam = 1.2679
+
+//    0.7321*x1 + x2 = 0
+//    x1 + 1.7321*x2 + x3 = 0
+//    Taking x1= 1.0, we have the approximate eigenvector 
+
+//                    x = [1.0000 -0.73210 0.26807]
+
+
+//    Compared with the true answer obtained above, this is a slightly poorer
+//    result obtained by inverse iteration.
+\ No newline at end of file