My code does not work

%Input parameters
Tt = 3000; %Kelvin
Pt = 1500; %[kPa]
mfr = 10; %[kg/s]
R = 8.314;
cp = 2;
cv = 2;

v_idex = sqrt(2*9.8*R*Tt);

[T_e, p_e, rho_e] = IdealGas(Tt, pt, v_e, mfr);

Unrecognized function or variable 'pt'.

gamma = cp/cv;



%method of chracteristic calculation
M = zeros(1,100);
T = zeros(1,100);
rho = zeros(1,100);
v = zeros(1,100);
p = zeros(1,100);

%plot M
plot(x, M);
xlabel('x');
ylabel('M');


%plot pressure
plot(x, pt);
xlabel('x');
ylabel('p (kPa)');

%plot Temp
plot(x, T);
xlabel('x');
ylabel('T Kelvin');



%plot density_rho
plot(x, rho);
xlabel('x');
ylabel('rho');

%plot velocity magnitude
plot(x, v_idex )
xlabel('x');
ylabel('velocity magnitude (m/s)');

[Stephen23]

Pt % what you defined
pt % what you used

Note the capitalisation.

Answer 1

[Sulaymon Eshkabilov]

Note also that there is one more undefined input vars in your function call. v_e is undefined, v_idex is computed from the given variables, R, Tt.

%Input parameters
Tt = 3000; %Kelvin
Pt = 1500; %[kPa]
mfr = 10; %[kg/s]
R = 8.314;
cp = 2;
cv = 2;

v_idex = sqrt(2*9.8*R*Tt);   % v_idex is known

[T_e, p_e, rho_e] = IdealGas(Tt, pt, v_e, mfr);  
%%%    v_e = ?