WHY THIS ERROR OCCUR ''??? Subscript indices must either be real positive integers or logicals."

t=-5 :0.1 :10;
h2=zeros(size(t));
h1=zeros(size(t));
z=zeros(size(t));
z=1*(t==0);
h2(t>=0)=exp(-t(t>=0));
h1(t>=0)=exp(-2*t(t>=0));
y1=conv(z,h1);
tn=t(1)+t(1):.1:t(end)+t(end);
y3=conv(z,h2);
y(tn)=y1+y3;
plot(tn,y);
hold on
y2(tn)=h1+h2;
plot(tn,y2)
ylabel('y1(t)=x(t)*h(t)');
xlabel('time[sec]');
grid;

Answer 1

[Kye Taylor]

Rethink how you're defining/using the variable

tn

Answer 2

[Wayne King]

The problem is that you have a vector, tn, that goes in increments of 0.1, but you cannot access elements of another vector y() using that.

The elements of y() have to be accessed using a positive integer between 1 and the length of y.

For example,

    y = randn(100,1);
    y(5:10)

You are trying to do this:

    y(3.1)