why I receive this error "Array indices must be positive integers or logical values"?

i'm trying fo run this function but i obtain this error "Array indices must be positive integers or logical values"

function c1a = c1a(w,r,gamma,beta)
c1a = (w + (w/(1+r)))/(1 + ((1/(1+r))*((beta(1+r))^gamma)) + ((1/(1+r)^2)*(beta*(1+r))^(2*gamma)));
end

gamma = 0.5;
beta = 0.9;
w = 0.3;
r = 1.2;

[c1star] = c1a(w,r,gamma,beta) 

%this is the error

Array indices must be positive integers or logical values.

Error in c1a (line 2)

c1a = (w + (w/(1+r)))/(1 + ((1/(1+r))*((beta(1+r))^gamma)) + ((1/(1+r)^2)*(beta*(1+r))^(2*gamma)));

Error in pseHomework (line 6)

[c1star] = c1a(0.3,1.2,0.5,0.9)

thanks to everyone

Answer 1

[Chunru]

gamma = 0.5;
beta = 0.9;
w = 0.3;
r = 1.2;
[c1star] = c1a(w,r,gamma,beta) 

c1star = 0.2130

function c1a = c1a(w,r,gamma,beta)
    %                                           *
    c1a = (w + (w/(1+r)))/(1 + ((1/(1+r))*((beta*(1+r))^gamma)) + ((1/(1+r)^2)*(beta*(1+r))^(2*gamma)));
end

[Andrea Sarli]

thank you so much!