Error in following matlab code.

Error in following codes

for i = 1:12
    if i == 12
        x1 = 9
    end    
    x1 = [1];
    x2 = [3];
    if i == 1
      x1 = 2
    else
    x1(i) = x1(i-1) - x2; 
    end
    x = [x1 x2]
end

When i run it it shows following error please help me to solve error.

Array indices must be positive integers or logical values.

[madhan ravi]

What is your desired result ? Give an example.

[Usman Taya]

I want 12 values of x1 and x2 where current x1 from i = 2 to 12 will calculate using x1(i) = x(i-1) -x2.

[Image Analyst]

Yes, but did Star's answer below solve your problem or not? Did you even try it?

Answer 1

[Star Strider]

The error comes from your current calculation of ‘x1’ as:

x1(i) = x1(i-1) - x2; 

In the first iteration,i=1 so (i-1)=0. In MATLAB, indices are integers greater than 0, or logical values.

I am not certain this ‘corrected’ version of your code creates the values for ‘x’ that you want. However, it has the virtue of running without error:

for i = 1:12
    if i == 12
        x1(i) = 9;
    end
    x1(i) = [1];
    x2 = [3];
    if i == 1
        x1(i) = 2;
    else
        x1(i+1) = x1(i) - x2;
    end
    x(i,:) = [x1(i) x2];
end

Experiment to get the result you want.