How can I rectify the parse error at '=' in line 7?

function ethylene
T = 306; % Temperature in K
P = 13.5; % Pressure in bar
R = 0.0831; % Gas constant in L*bar*K^-1
B = -140000; % B in L*(mol)^-1
C = 7200000; % C in L^2*(mol)^-2
1+(B/V)+(C/V^2) = P*V/R/T; % Volume in L
fprintf('The volume of ethylene is %d L\n',V)
end

[KSSV]

What is this line?

1+(B/V)+(C/V^2) = P*V/R/T; % Volume in L

Answer 1

[Jonas Allgeier]

In line eight, you want to print the value of V. The problem is, you never assign it any value. Variable assigment in essence always requires a line like

V = ...

In your code however, you seem to provide an equation that could be solved for V. This is no direct assignment and Matlab therefore does not know what to do with this line.

To rectify this error, you would need to have an equation that already is solved for V. Otherwise you could also use some kind of optimization technique to find the solution of this equation by iteratively testing different values until the equation is (nearly) met.

[Walter Roberson]

fsolve() an expression which is the left side minus the right side