'For' loop conditions

for chek= 1:length(d)-1
    if c(chek)+20>20;
        nmm=MM(c(chek):c(chek)-20,chek)  ; 
        mn=MM((c(chek)-20:c(chek)),chek) ;
        C{chek}=mn;
        X{chek}=nmm;
    else
        c(chek)+20<20
        mn=0 ;
        nmm=0  ;
        C{chek}=mn;
        X{chek}=nmm;
    
    end
end

Help please, I have a cycle, I work with 'c', I know that some of its values ​​= 0, first add the essence of the cycle 20 to 'c', then back.

The error is that X knocks out all zeros.

With the values ​​of 'C' everything is fine

[David Goodmanson]

Hi Lev,

abbreviating c(chek) as b, then

b:b-20 produces: 1×0 empty double row vector

and

 b:-1:b-20

produces a vector of descending values.

[Geoff Hayes]

Lev - perhaps this

    else
        c(chek)+20<20

should read

    elseif c(chek)+20<20

instead. Also, I'm not sure I understand why you subtract 20 from the following

    nmm=MM(c(chek):c(chek)-20,chek)  ; 
    mn=MM((c(chek)-20:c(chek)),chek) ;

Please clarify.