I keep on getting 'index exceeds array bounds'

>> i=1; >> x1(i)=1;x2(i)=1;x3(i)=1; >> error_x1(i)=999999999999999999999999; >> while error_x1(i)>=0.01 x1(i+1) = (7-x2(i)-3*x2(i))/2 x2(i+1) = (9-3*x1(i+1)+2*x3(i))/4 x3(i+1) = (4-x2(i+1)-x3(i+1))/1

         error_x1(i+1) = abs((x1(i+1)-x1(i))/x1(i+1))*100;
         error_x1(i+1) = abs((x2(i+1)-x2(i))/x2(i+1))*100;
         error_x1(i+1) = abs((x3(i+1)-x3(i))/x3(i+1))*100;

         i=i+1;
end

x1 =

    1.0000    1.5000

x2 =

    1.0000    1.6250

Index exceeds array bounds.

Answer 1

[Ji Hoon Jeong]

I presume this is your code.

i=1;
x1(i)=1;
x2(i)=1;
x3(i)=1;
error_x1(i)=999999999999999999999999;

while error_x1(i)>=0.01 
    x1(i+1) = (7-x2(i)-3*x2(i))/2 
    x2(i+1) = (9-3*x1(i+1)+2*x3(i))/4 
    x3(i+1) = (4-x2(i+1)-x3(i+1))/1

      error_x1(i+1) = abs((x1(i+1)-x1(i))/x1(i+1))*100;
      error_x1(i+1) = abs((x2(i+1)-x2(i))/x2(i+1))*100;
      error_x1(i+1) = abs((x3(i+1)-x3(i))/x3(i+1))*100;
      i=i+1;
  end

The third line in your while statement is causing the problem.

x3(i+1) term in the right side of the equal sign.

Since x3(1+1) does not exist, you should change your algorithm.