code changes by Kartik Hegde during FOSSEE Fellowship 2018

1 files changed, 40 insertions, 12 deletions

diff --git a/macros/cconv.sci b/macros/cconv.sci
index c7560ef..d3c2c2f 100644
--- a/macros/cconv.sci
+++ b/macros/cconv.sci
@@ -1,12 +1,40 @@
 //Author: Parthasarathi Panda
 //parthasarathipanda314@gmail.com
 function o=cconv(a,b,n)
+
+ // circularly convolves vectors a and b. n is the length of the resulting vector.
+ //If you omit n, it defaults to length(a)+length(b)-1. When n = length(a)+length(b)-1,
+ //the circular convolution is equivalent to the linear convolution computed with conv
+ //Calling Sequence:
+ //o=cconv(a,b)
+ //o = cconv(a,b,n)
+//a  =a real or complex vector.
+//b  =a real or complex vector.
+//n  =length of circular convolution
+//o  =convolution sequence
+//Examples:
+//a=[1 2 3]
+//b=[4 5 6]
+//o=cconv(a,b,3)
+//Output:  o=  31.    31.    28.
+//
+//
+//a=[1 2+%i 4]
+//b=[2 3*%i 5]
+//o=cconv(a,b)
+//o=clean(o)
+//
+//Output:  o=  2.    4. + 5.i    10. + 6.i    10. + 17.i    20.
+//
+
+
+
     [nargout,nargin]=argn();
-    if nargin==2 then
-        n=length(a)+length(b)-1;
+    if nargin==2 then //to check the number of inputs entered by the user
+        n=length(a)+length(b)-1;//setting the length of convolution
     end
-    if type(a)~=1 | type(b)~=1 | type(n)~=1 then
-        error('check the data type of input'); //to check if the inputs are real/complex arrays
+    if type(a)~=1 | type(b)~=1 | type(n)~=1 then//to check if the inputs are real/complex arrays
+        error('check the data type of input');
     end
     if size(n)~=[1,1] then
         error('check the data type of input'); //to check that n is single dimensional
@@ -18,27 +46,27 @@ function o=cconv(a,b,n)
     [i,j]=size(a);
     if j~=1 & i~=1 then
         error('a should be a vector');
-    elseif j==1 
+    elseif j==1 //if a column vector make it a row vector
         a=a';
     end
     //checking if b is a 1d vector(row or column) and turning it into row vector
     [i,j]=size(b);
     if j~=1 & i~=1 then
         error('b should be a vector');
-    elseif j==1 
+    elseif j==1//if a column vector make it a row vector
         b=b';
     end
-    
+
     //adjusting length of a
-    if n<=length(a) then
+    if n<=length(a) then//if length exceeds n,then take only first n-samples
         a=a(1:n);
-    else
+    else//if length is less than n, then pad zeroes
         a=[a,zeros(1,n-length(a))]
     end
     //adjusting length of b
-    if n<=length(b) then
+    if n<=length(b) then//if length exceeds n,then take only first n-samples
         b=b(1:n);
-    else
+    else//if length is less than n, then pad zeroes
         b=[b,zeros(1,n-length(b))]
     end
     //computing ffts (for speed)
@@ -46,5 +74,5 @@ function o=cconv(a,b,n)
     bft=fft(b);
     //circular convolution dft is the product of dft of the 2
     oft=aft.*bft;
-    o=ifft(oft);    
+    o=ifft(oft);  //inverse gives circular covolution
 endfunction