Thread Subject: simple average magitude diff

Hello everyone,
  How can I implement the following segment without getting the error:
"Subscript indices must either be real positive integers or logicals."
for k=0:N-1
     for n=0:N-1
         amdf(k)=(1/N)*sum(y(n)-y(n-k));
        figure(1)
         plot(amdf)
     end
 end
Thanx.

"astro mmi" <pyarsa_madhu@yahoo.co.in> wrote in message <he9ubc$q8s$1@fred.mathworks.com>...
> Hello everyone,
> How can I implement the following segment without getting the error:
> "Subscript indices must either be real positive integers or logicals."
> for k=0:N-1
> for n=0:N-1
> amdf(k)=(1/N)*sum(y(n)-y(n-k));
> figure(1)
> plot(amdf)
> end
> end
> Thanx.

for example:

for k=1:N
     for n=1:N
       try
         amdf(k)=(1/N)*sum(y(n)-y(n-k));
     catch
     disp 'Index n-k is not between 1 and length(y). Skipping...'
     end



        figure(1)
         plot(amdf)
     end
 end

"astro mmi" <pyarsa_madhu@yahoo.co.in> wrote in message <he9ubc$q8s$1@fred.mathworks.com>...
> Hello everyone,
> How can I implement the following segment without getting the error:
> "Subscript indices must either be real positive integers or logicals."
> for k=0:N-1
> for n=0:N-1
> amdf(k)=(1/N)*sum(y(n)-y(n-k));
> figure(1)
> plot(amdf)
> end
> end
> Thanx.

I wish Matlab would number the first cell in a vector with the '0'.

Yet, Matlab counting (Of the cells number) starts with '1'.

Hence you can't access cell with Vector_Name(0) as you do in your code.

"Royi Avital" <RoyiREMOVEAvital@yahoo.com> wrote in message <hea0q5$phk$1@fred.mathworks.com>...

> I wish Matlab would number the first cell in a vector with the '0'.
>
> Yet, Matlab counting (Of the cells number) starts with '1'.
>
> Hence you can't access cell with Vector_Name(0) as you do in your code.

Well, that wasn't the only problem. The expression 'n-k' was generating all kinds of other out of bounds indices as well.

In any case, if you really want to be able to index matrices starting from 0, you can make your own data type, as I've done for you at the bottom of this post.

Example of usage:

>> A=ZeroBased(1:5)
 
A =
 
     1 2 3 4 5


>> A(0:2)=A(0:2)*10
 
A =
 
    10 20 30 4 5



%%%%%%%Code below must go in a file called ZeroBased.m

classdef ZeroBased < double
%ZeroBased - a class essentially the same as @double, but can be indexed
%starting from 0.

    methods
       
        function obj=ZeroBased(data)
            %constructor for ZeroBased

            obj=obj@double(data);
            
        end
        
        function objnew=subsref(obj,S)
        %SUBSREF for ZeroBased class
        
            nn=length(S.subs);
            for ii=1:nn
             if ~(ischar(S.subs{ii})|islogical(S.subs{ii})),
              S.subs{ii}=S.subs{ii}+1;
             end
            end

            objnew=subsref@double(obj,S);

            
        end

        
        function objnew=subsasgn(obj,S,rhs)
        %SUBSASGN for ZeroBased class
            
            nn=length(S.subs);
            for ii=1:nn
             if ~(ischar(S.subs{ii})|islogical(S.subs{ii})),
              S.subs{ii}=S.subs{ii}+1;
             end
            end

            objnew=subsasgn@double(obj,S,rhs);
            
        end
        
        function display(obj)
            
            l=inputname(1);
            if isempty(l), l='ans'; end
            disp ' '
            disp([l ' = ']);
            disp ' '
            disp(double(obj));
            
        end
        
        
        function obj=uplus(obj)
            
        end

        function obj=uminus(obj)
            
            obj=ZeroBased(-double(obj));
            
        end
        
        function obj=plus(L,R)
            
          obj = ZeroBased( double(L)+double(R) );
            
        end

        function obj=minus(L,R)
            
          obj = ZeroBased( double(L)-double(R) );
            
        end
        
        
        
       function obj=times(L,R)
            
          obj = ZeroBased( double(L).*double(R) );
            
        end

        function obj=mtimes(L,R)
            
          obj = ZeroBased( double(L)*double(R) );
            
        end
        
         function obj=rdivide(L,R)
            
          obj = ZeroBased( double(L)./double(R) );
            
        end

        function obj=ldivide(L,R)
            
          obj = ZeroBased( double(L).\double(R) );
            
        end
        
        function obj=mrdivide(L,R)
            
          obj = ZeroBased( double(L)/double(R) );
            
        end

        function obj=mldivide(L,R)
            
          obj = ZeroBased( double(L)\double(R) );
            
        end
        
        
    end
    
end