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+// Procedure to split a polynomial into good and bad factors, as discussed in Sec. 9.2.
+// 9.3
+// function [goodpoly,badpoly] = polsplit2(fac,a)
+// Splits a scalar polynomial of z^{-1} into good and bad 
+// factors. 
+// Input is a polynomial in increasing degree of z^{-1}
+// Optional input is a, where a <= 1.
+// Factor that has roots of z^{-1} outside a is called
+// good and the rest bad.
+// If a is not specified, it will be assumed as 1-1.0e-5
+
+function [goodpoly,badpoly] = polsplit2(fac,a)
+if argn(2) == 1, a = 1-1.0e-5; end  
+if a>1 error('good polynomial is unstable'); end
+fac1 = poly(fac(length(fac):-1:1),'z','coeff');
+rts1 = roots(fac1);
+rts = rts1(length(rts1):-1:1);
+
+// extract good and bad roots
+badindex = find(abs(rts)>=a); // mtlb_find has been replaced by find
+badpoly = coeff(poly((rts(badindex)),"z","roots"));
+goodindex = find(abs(rts)<a); // mtlb_find has been replaced by find
+goodpoly = coeff(poly(rts(goodindex),"z","roots"));
+
+// scale by equating the largest terms
+[m,index] = max(abs(fac));
+goodbad = convol(goodpoly,badpoly);
+goodbad1 = goodbad(length(goodbad):-1:1);//--
+factor1 = fac(index)/goodbad1(index);//--
+goodpoly = goodpoly * factor1;
+goodpoly = goodpoly(length(goodpoly):-1:1);
+badpoly = badpoly(length(badpoly):-1:1);
+endfunction;
+
+
+