Matrix Dimensions must agree

FUNCTION:

function P = preos_P(V, T, Pc, Tc, w)

R = 8.314;

Tr = T./Tc;

a = 0.4572355289.*(R.^2.*T.^2./Pc);

b = 0.0777960739*(R.*Tc./Pc);

k= 0.37464+1.54226.*w-0.26992.*w.^2;

alpha = (1+k.*(1-Tr.^1/2)).^2;

P = (R.*T./(V-b))-(alpha.*a)/(V.^2+2.*b.*V-b.^2);

end

% takes inputs of temperature (T ), volume (V ), critical pressure (Pc),

% critical temperature (Tc), and acentric factor (w) and returns the pressure.

SCRIPT:

% takes inputs of temperature (T ), volume (V ), critical pressure (Pc),

% critical temperature (Tc), and acentric factor (w)

% and returns the pressure.

clear; clc

T = linspace(273, 373, 100)'; %Temperature in K

Tc = [304.2 190.6 419.6];

Pc = [7.382 4.604 4.02];

w = [0.228 0.011 0,187];

V = .1*1000;

R = 8.314;

P = preos_P (V, T, Pc, Tc, w);

Ps = P;

Ts = T;

plot(Ts,Ps)

legend('carbon dioxide', 'methane', '1-butene', 'Location', 'NorthWest')

title ('[ressures of gases')

Answer 1

[madhan ravi]

• T has 100 elements whereas Tc has only 3 (reason for the error) , both should have same number of elements

T./Tc % here

• Matlab interprets that w has 4 elements

w = [0.228 0.011 0,187];
               %  ^----- has to be a dot

If all the above statements are fulfilled plot can be expected.