subscript indices error issue

clear all
close all
r=[0.1,1.5];
beta=[34.0:34.5:35];
w=1.2;
D=6.0;
gamma=1.5;
K=-26.5487652;
xi=[1.5:3.0:4.5];
rho=1.2;
e=0.9;
z=(rho.*(r.^w))./(xi);
q = (gamma*e)./z;
Kp=2;
L=((gamma+1)*xi-(gamma-1))./((gamma+1)-(gamma-1)*xi);
K1=(2*pi)./((2*w-1)*(2-w)*D);
chi=((gamma*(gamma-1)*(xi-1).^3)./(2*xi(((2-gamma)*xi)+gamma)));
C5=(((2*(L-xi^2)*chi)*chi)./(gamma))./((chi./gamma)^2-((chi./4*gamma)*(xi-1)^2));
C6=(((2*L*chi)./gamma)+ ((chi*sqrt(chi*xi))./(chi-1-chi*xi))*((chi-1)^2*sqrt(chi./xi)+2*(chi./xi)*sqrt(chi*xi)))./((chi./gamma)^2-(chi./(4*gamma))*(xi-1)^2);
B=((((chi*(xi-1))./((xi-1)-sqrt(chi*xi)))-(chi*w./gamma))*(2*chi./gamma))./((chi./gamma)^2-(chi./4*gamma)*(xi-1)^2);
y=(((K1*r^(1-2*w))*gamma)-(1.5*gama*beta*r)+K).*((chi.*{(((K1*r^(1-w))*gamma)-(1.5*gama*beta*r^(1+w))+(K*r^w))}^-1.*{(Kp*r^-B)./(z)+((C5*beta*r^(w+1))./(1+w+B))+((2*pi*C6*r^(1-w))./(D*(2-w)*(1-w+B)))}+L));
plot(y,r);

Subscript indices must either be real positive integers or logicals.

Error in problem_17 (line 18)

chi=((gamma*(gamma-1)*(xi-1).^3)./(2*xi(((2-gamma)*xi)+gamma)));

please help me to fix this error.

Thank you

[Manas Minnoor]

Hi Sewa,

Are you trying to index into the array xi with the following code?

 (2*xi(((2-gamma)*xi)+gamma))

Or did you intend to multiply xi with the result of

(((2-gamma)*xi)+gamma)