1 files changed, 52 insertions, 22 deletions
diff --git a/macros/blackmannuttall.sci b/macros/blackmannuttall.sci
index 29dd1b0..674afe9 100644
--- a/macros/blackmannuttall.sci
+++ b/macros/blackmannuttall.sci
@@ -1,34 +1,64 @@
-function [w] = blackmannuttall (m, opt)
+//function [w] = blackmannuttall (m, opt)
 //This function returns the filter coefficients of a Blackman-Nuttall window.
 //Calling Sequence
 //w = blackmannuttall (m)
 //w = blackmannuttall (m, opt)
-//Parameters 
+//Parameters
 //m: positive integer value
 //opt: string value, takes "periodic" or "symmetric"
 //w: output variable, vector of real numbers
-//Description. 
+//Description.
 //This is an Octave function.
-//This function returns the filter coefficients of a Blackman-Nuttall window of length m supplied as input, to the output vector w. 
-//The second parameter can take the values "periodic" or "symmetric", depending on which the corresponding form of window is returned. The default is symmetric. 
+//This function returns the filter coefficients of a Blackman-Nuttall window of length m supplied as input, to the output vector w.
+//The second parameter can take the values "periodic" or "symmetric", depending on which the corresponding form of window is returned. The default is symmetric.
 //Examples
 //blackmannuttall(5,"symmetric")
 //ans  =
-//    0.0003628  
-//    0.2269824  
-//    1.         
-//    0.2269824  
-//    0.0003628 
-rhs = argn(2)
-
-if (rhs<1 | rhs>2)
-error("Wrong number of input arguments.")
-end
-	select (rhs)
-	case 1 then
-	w = callOctave("blackmannuttall",m)
-	case 2 then
-	w = callOctave("blackmannuttall",m,opt)
-	end
-endfunction
+//    0.0003628
+//    0.2269824
+//    1.
+//    0.2269824
+//    0.0003628
+
+
+
+
+function w = blackmannuttall (m, opt)
+
+ funcprot(0);
+    rhs= argn(2);
 
+  if (rhs < 1 | rhs > 2)
+     error("Wrong Number of input arguments");
+  end
+
+  if (~ (isscalar (m) & (m == fix (m)) & (m > 0)))
+    error ("blackmannuttall: M must be a positive integer");
+  end
+
+  N = m - 1;
+  if (rhs == 2)
+    select (opt)
+      case "periodic"
+        N = m;
+      case "symmetric"
+        N = m-1;
+      else
+        error ('nuttallwin: window type must be either periodic or symmetric");
+    end
+  end
+
+    if (m == 1)
+        w = 1;
+    else
+        a0 = 0.3635819;
+        a1 = 0.4891775;
+        a2 = 0.1365995;
+        a3 = 0.0106411;
+//        n = [-N/2:(m-1)/2]';
+//        w = a0 + a1.*cos(2.*%pi.*n./N) + a2.*cos(4.*%pi.*n./N) + a3.*cos(6.*%pi.*n./N);
+        n=[0:m-1]'
+        w = a0 - a1.*cos(2.*%pi.*n./N) + a2.*cos(4.*%pi.*n./N) - a3.*cos(6.*%pi.*n./N);
+     end
+
+endfunction