How to set y to different functions depending on the limits of T

So I'm trying to program this into matlab:

where ai is 0.5 and a0 is 0.3. I have tried using this code for it but I'm having difficulty with the (-10 <= T && T <= 10) part. Many Thanks!

T = -20:0.5:20;
ai = 0.5;
a0 = 0.3;

if T <= -10
    y = ai
end

if (-10 <= T && T <= 10)
    y = ai + (a0 - ai)*((T+10)/20)
end

if 10 <= T
    y = a0
end

plot(T, y, 'bo-');
grid on;

Answer 1

[Alan Stevens]

Might be easier as

T = -20:0.5:20;
ai = 0.5;
a0 = 0.3;
y = ai + (a0 - ai)*((T+10)/20);
id = find(T<=-10);
y(id) = ai;
id = find(10<=T);
y(id) = a0;

plot(T, y, 'bo-');
grid on;