code by jitendra

1 files changed, 25 insertions, 12 deletions

diff --git a/macros/sos2zp.sci b/macros/sos2zp.sci
index 98abc36..1f0f335 100644
--- a/macros/sos2zp.sci
+++ b/macros/sos2zp.sci
@@ -11,7 +11,6 @@ function [z,p,k] = sos2zp (sos, g)
 //z: column vector
 //p: column vector
 //Description
-//This is an Octave function. 
 //This function converts series second-order sections to zeros, poles, and gains (pole residues).
 //The input is the sos matrix and the second parameter is the overall gain, default value of which is 1.
 //The outputs are z, p, k. z and p are column vectors containing zeros and poles respectively, and k is the overall gain. 
@@ -24,18 +23,32 @@ function [z,p,k] = sos2zp (sos, g)
 //  -0.6250 + 1.0533i
 //  -0.6250 - 1.0533i
 //c =  1
-
-funcprot(0);
-rhs = argn(2)
-if(rhs<1 | rhs>2)
+if(argn(2)<1 | argn(2)>2)
 error("Wrong number of input arguments.")
 end
+if argn(2)==1 then
+    g=1;
+end
+  gns = sos(:,1); 
+  k = prod(gns)*g; 
+  if k==0 then
+     error('one or more section gains is zero'); 
+     end
+  sos(:,1:3) = sos(:,1:3)./ [gns gns gns];
 
-	select(rhs)
-	case 1 then
-	[z,p,k] = callOctave("sos2zp",sos)
-	case 2 then
-	[z,p,k] = callOctave("sos2zp",sos,g)
-	end
-endfunction
+  [N,m] = size(sos);
+  if m~=6 then
+      error('sos matrix should be N by 6'); 
+      end
 
+  z = zeros(2*N,1);
+  p = zeros(2*N,1);
+  for i=1:N
+    ndx = [2*i-1:2*i];
+    zi = roots(sos(i,1:3));
+    z(ndx) = zi;
+    pi = roots(sos(i,4:6));
+    p(ndx) = pi;
+  end
+
+endfunction