1 files changed, 30 insertions, 21 deletions
diff --git a/macros/isstable.sci b/macros/isstable.sci
index db7d5b5..16cf5a2 100644
--- a/macros/isstable.sci
+++ b/macros/isstable.sci
@@ -1,26 +1,35 @@
-//isstable True for stable filter
-//  FLAG = ISSTABLE(B,A) returns a logical output, FLAG, equal to TRUE if
-//  the filter specified by numerator coefficients B, and denominator
-//  coefficients A, is stable. Input vectors B, and A define a filter with
-//  transfer function:
-//
-//              jw               -jw              -jmw
-//       jw  B(e)    b(1) + b(2)e + .... + b(m+1)e
-//    H(e) = ---- = ------------------------------------
-//              jw               -jw              -jnw
-//           A(e)    a(1) + a(2)e + .... + a(n+1)e
-//
-//  FLAG = ISSTABLE(SOS) returns TRUE if the filter specified using the
-//  second order sections matrix, SOS, is stable. SOS is a Kx6 matrix,
-//  where the number of sections, K, must be greater than or equal to 2.
-//  Each row of SOS corresponds to the coefficients of a second order
-//  filter. From the transfer function displayed above, the ith row of the
-//  SOS matrix corresponds to [bi(1) bi(2) bi(3) ai(1) ai(2) ai(3)].
+//Checks for stability of Discrete time System function
+
+//Description :  A  Discrete time system is stable if all poles of system function are inside unit circle
+
 //  Calling Syntax
 //  flag=isstable(b,a);
 //  flag=isstable(sos);
-//Author: Parthasarathi Panda
-//parthasarathipanda314@gmail.com
+
+//It takes input b and a which are array vector of numerator and denumerator coefficients respectively also it takes second order section (sos) system function input.SOS is a Kx6 matrix,where the number of sections, K, must be greater than or equal to 2.Each row of SOS corresponds to the coefficients of a second order filter
+//It returns a logical flag = 1(true) if given system is stable and 0(false) otherwise
+
+// Eample : 1
+// flag = isstable([1 2],[1 -0.7 0.1])
+
+// Output:
+// flag  =
+//
+//    1.
+
+// Conclusion : as flag output is 1 system is stable
+
+// Example : 2
+// flag = isstable([1 2 0],[1 5 6])
+
+//Output :
+//unstable system
+// flag  =
+//
+//    0.
+
+// Conclusion : this system is unstable as flag output is 0
+
 function isstab=isstable(varargin)
 [nargout,nargin]=argn();
 if (nargin==2) then//(a,b) is the input
@@ -59,7 +68,7 @@ elseif (nargin==1) then//sos form is given as input
         if type(sos)~=1 then
             error('check input type');
         end
-        
+
         if length(v)>2 then
             error('check input dimension');
         end