How to subtract previous array element from the current one ?

I have datastream as lines from the comport. All values are being parsed and I can choose the interested data. In this case, I want to subtract previous Easting value from the current one and calculate the distance between these two values each second when new string received. Could not create a 'for' loop for this operation;

s=serialport('COM14',115200);
configureTerminator(s,"CR/LF");
t = 0;
a = 0;
while true
    t = t + 1;
    line=readline(s);
    ld=split(line,',');
        Date=(ld{1});
        UTC=(ld{2});
        
        LAT=(str2double(ld{3}));
        LONG=(str2double(ld{4}));
        ALT=(str2double(ld{5}));
        [Easting,Northing,UTMZone]=deg2utm(LAT,LONG);
        HPOS=[Easting Northing];

       
        SoG=(ld{6});
        Depth=(ld{7});
        CL=(ld{8});
        
        AX=(str2double(ld{9}));
        AY=(str2double(ld{10}));
        AZ=(str2double(ld{11}));
        
        GX=(str2double(ld{12}));
        GY=(str2double(ld{13}));
        GZ=(str2double(ld{14}));
        
        MX=(str2double(ld{15}));
        MY=(str2double(ld{16}));
        MZ=(str2double(ld{17}));
        
        Temp=(ld{18});
        Bat=(ld{19});
        
        ii=1:length(Date);
        jj=2:length(Date);
        test=zeros(length(HPOS),1);
        
        for ix=1:length(Date)
           
            test(ix)=HPOS(jj)-HPOS(ii);
            
        end
      

end

when I run this code, I get the error message saying;

Index exceeds the number of array elements (2).
Error in Untitled5 (line 46)
    test(ix)=HPOS(jj)-HPOS(ii);

Kind Regards,

Alper

Answer 1

[Scott MacKenzie]

If you want to

subtract previous Easting value from the current one

see below. The value you want is EastingDiff.

EastingSave = 0;
while true
    ...
   [Easting,Northing,UTMZone]=deg2utm(LAT,LONG);
    EastingDiff = Easting - EastingSave;
    EastingSave = Easting;
    ...
end

To avoid the error, get rid of the six lines beginning with ii = . You don't need them.

[Mustafa Alper Cetintas]

Appreciated ! That is what I was exactly looking for, thank you Sir.