Trying to mask can anyone help?

%%

choose_in = input('Please enter a psoition between 0 and 360  ');
if (choose_in < 0)
     choose_in = abs(choose_in);
    Warning('You entered a negative value, taking the ablsolute value');
   
end

if (choose_in > 360)
    error('The value is greater than 360 inches, program terminated')
end

a=(0:360); %number 0-choose_in
mask1= a(b);
b= a>=120;
mask2= a>240 & a<360;
Deflection = (1/(3.19*10^9)) * ((((800*choose_in^3) - 13.68 * ((10^6)*choose_in) - (2.5*choose_in^4) + (2.5*((choose_in-120)^4)*((mask1)) + (600*((choose_in-240)^3*(mask2)))))))
%Deflection = Deflection_ahdoan2(choose_in);

[Rik]

What do you mean with mask in your context? Also, you forgot to properly format your question.

[Alex Doan]

Logical indexing is what's its called

[KSSV]

What you are trying to do in the code? What probelm you facing in the code?

mask1= a(b);

In the above line, what is b? It is not defined and used in the code.