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diff --git a/2048/DEPENDENCIES/specfac.sci b/2048/DEPENDENCIES/specfac.sci
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+// Spectral factorization, to solve Eq. 13.47 on page 471.
+// 13.3
+
+// function [r,b,dAFW] = ...
+//    specfac(A,degA,B,degB,rho,V,degV,W,degW,F,degF)
+// Implements the spectral factorization for use with LQG control
+// design method of Ahlen and Sternard
+
+function [r,b,dAFW] = ...
+   specfac(A,degA,B,degB,rho,V,degV,W,degW,F,degF)
+AFW = convol(A,convol(W,F));
+dAFW = degA + degF + degW;
+AFWWFA = rho * convol(AFW,flip(AFW));
+BV = convol(B,V);
+dBV = degB + degV;
+BVVB = convol(BV,flip(BV));
+diff1 = dAFW - dBV;
+dBVVB = 2*dBV;
+for i = 1:diff1
+    [BVVB,dBVVB] = polmul(BVVB,dBVVB,[0 1],1);
+end
+[rbb,drbb] = poladd(AFWWFA,2*dAFW,BVVB,dBVVB);
+Rbb = polyno(rbb,'z');
+rts = roots(Rbb);
+rtsin = rts(dAFW+1:2*dAFW);
+b = 1;
+for i = 1:dAFW,
+    b = convol(b,[1 -rtsin(i)]);
+end
+b = real(b); 
+br = flip(b);
+bbr = convol(b,br);
+r = rbb(1) / bbr(1);
+endfunction;