ecgdemowinmax.m

%   ECGDEMO    ECG PROCESSING DEMONSTRATION - R-PEAKS DETECTION
           
function Filtered=ecgdemowinmax(Original, WinSize)
    %initialising variables
    
    WinHalfSize = floor(WinSize/2);
    WinHalfSizePlus = WinHalfSize+1;
    WinSizeSpec = WinSize-1;
    FrontIterator = 1;
    WinPos = WinHalfSize;
    WinMaxPos = WinHalfSize;
    WinMax = Original(1);
    OutputIterator = 0;
    
    % Finding the postion of the largest value in window
    
    for LengthCounter = 0:1:WinHalfSize-1 
        if Original(FrontIterator+1) > WinMax
            WinMax = Original(FrontIterator+1);
            WinMaxPos = WinHalfSizePlus + LengthCounter;
        end
        FrontIterator=FrontIterator+1;
    end
    
    % if the first point is the highest, set ouput 1
    
    if WinMaxPos == WinHalfSize 
        Filtered(OutputIterator+1)=WinMax;
    else
        Filtered(OutputIterator+1)=0;
    end
    OutputIterator = OutputIterator+1;
    
    % search next half of signal
    
    for LengthCounter = 0:1:WinHalfSize-1 
        if Original(FrontIterator+1)>WinMax
            WinMax=Original(FrontIterator+1);
            WinMaxPos=WinSizeSpec;
        else
            WinMaxPos=WinMaxPos-1;
        end
        if WinMaxPos == WinHalfSize
            Filtered(OutputIterator+1)=WinMax;
        else
            Filtered(OutputIterator+1)=0;
        end
        FrontIterator = FrontIterator+1;
        OutputIterator = OutputIterator+1;
    end
    for FrontIterator=FrontIterator:1:length(Original)-1
        if Original(FrontIterator+1)>WinMax
            WinMax=Original(FrontIterator+1);
            WinMaxPos=WinSizeSpec;
        else
            WinMaxPos=WinMaxPos-1;
            if WinMaxPos < 0
                WinIterator = FrontIterator-WinSizeSpec;
                WinMax = Original(WinIterator+1);
                WinMaxPos = 0;
                WinPos=0;
                for WinIterator = WinIterator:1:FrontIterator
                    if Original(WinIterator+1)>WinMax
                        WinMax = Original(WinIterator+1);
                        WinMaxPos = WinPos;
                    end
                    WinPos=WinPos+1;
                end
            end
        end
        if WinMaxPos==WinHalfSize
            Filtered(OutputIterator+1)=WinMax;
        else
            Filtered(OutputIterator+1)=0;
        end
        OutputIterator=OutputIterator+1;
    end
    WinIterator = WinIterator-1;
    WinMaxPos = WinMaxPos-1;
    for LengthCounter=1:1:WinHalfSizePlus-1
        if WinMaxPos<0
            WinIterator=length(Original)-WinSize+LengthCounter;
            WinMax=Original(WinIterator+1);
            WinMaxPos=0;
            WinPos=1;
            for WinIterator=WinIterator+1:1:length(Original)-1
                if Original(WinIterator+1)>WinMax
                    WinMax=Original(WinIterator+1);
                    WinMaxPos=WinPos;
                end
                WinPos=WinPos+1;
            end
        end
        if WinMaxPos==WinHalfSize
            Filtered(OutputIterator+1)=WinMax;
        else
            Filtered(OutputIterator+1)=0;
        end
        FrontIterator=FrontIterator-1;
        WinMaxPos=WinMaxPos-1;
        OutputIterator=OutputIterator+1;
    end