Why does the second matrix start with zeros?

for i=-10:10
    if i<0
        a(i+11)=i;
    if i>0 
        b(i+10)=i;
    end
    end
end

Out of curiosity, why, if I print b, would the matrix start with 10 zeros?

[Adam Danz]

"Out of curiosity, why, if I print b, would the matrix start with 10 zeros?"

This code should never reach 'b' which would leave 'b' undefined. The i>0 condition is nested within the i<0 condition. So if i<0, than i will never be greater than 0.

Here is your code with correct formatting.

for i=-10:10
    if i<0
        a(i+11)=i;
        if i>0
            b(i+10)=i;
        end
    end
end

My guess is that one of your 'end' lines is misplaced.

Even if you fix it, you'd still have problems getting what you want for reasons described by madhan ravi.

Answer 1

[madhan ravi]

MATLAB assigns zero to the previous indices, for better understanding:

 clear a 
 a(11) = 1; % now you will see elements from 1-10 are filled with zeros, if a doesn’t exist already in the workspace

Perhaps what you want is:

 ii = -10 : 10;
 a = ii(ii < 0)
 b = ii(ii >= 0)

[Spencer Checkoway]

Thank you!