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diff --git a/2048/CH13/EX13.2/spec1.sci b/2048/CH13/EX13.2/spec1.sci
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+// Function to implement spectral factorization, as discussed in sec. 13.1.
+// 13.2
+
+function [r,b,rbbr] = spec1(A,dA,B,dB,rho)
+AA = rho * convol(A,flip(A));
+BB = convol(B,flip(B));
+diff1 = dA - dB;
+dBB = 2*dB;
+for i = 1:diff1
+    [BB,dBB] = polmul(BB,dBB,[0 1],1);
+end
+[rbbr,drbbr] = poladd(AA,2*dA,BB,dBB);
+rts = roots(rbbr);  // roots in descending order of magnitude
+rts = flip(rts);
+rtsin = rts(dA+1:2*dA);
+b = 1;
+for i = 1:dA,
+    b = convol(b,[1 -rtsin(i)]);
+end
+br = flip(b);
+bbr = convol(b,br);
+r = rbbr(1) / bbr(1);
+endfunction;