Homogenuous differential equation with conditions

Find and draw the first 22 terms of the solution of the homogeneous differential equation with the initial conditions: y[−1] = 0.6, y[−2] =

-8.2.

I dont understand what went wrong here?Dont understand how this work.

j=22;

y=[-8.2,0.6];

for i= -8.2:j+0.6

y(i)= 0.19*y(i-1)-0.36*y(i-2)+(0.31)^(i-3);

end

k=[-2:21];

stem(k,y);

"Array indices must be positive integers or logical values" problem

Answer 1

[Dyuman Joshi]

j=22;
y=[-8.2,0.6];

As you can see below, you are using non integer values as an index, which is not possible.

i = -8.2:j+0.6

i = 1×31

-8.2000 -7.2000 -6.2000 -5.2000 -4.2000 -3.2000 -2.2000 -1.2000 -0.2000 0.8000 1.8000 2.8000 3.8000 4.8000 5.8000 6.8000 7.8000 8.8000 9.8000 10.8000 11.8000 12.8000 13.8000 14.8000 15.8000 16.8000 17.8000 18.8000 19.8000 20.8000

MATLAB accepts only Natural numbers as index values. [1 2 3 4 ....] (or logical values, as the error clearly states)

Change the loop variable values

for i=3:22
   y(i)= 0.19*y(i-1)-0.36*y(i-2)+(0.31)^(i-3);
end
k=[-2:19];
stem(k,y)