Need help inputting my equation into MATLAB

(R*(sin((pi*t)/12))^4 + R0)*(Q) - (Q+P)*((M(t))/((V-Q)*t))

The above equation is what I want to input, like this....

%% seawater.m

% Setup equation parameters

V = 10000; Q = 1000; P = 200; R = 10; R0 = 25; M0 = 0;

% Choose a time step h for Euler's method and the inteval [0,tf]

h = 0.01; tf = 120;

t = 0:h:tf;

M = zeros(1,length(t));

M(1) = M0;

% Enter the right side of the differential equation for M

% in terms of P, Q, R, R0 and V.

f = @(t,M) (R*(sin((pi*t)/12))^4 + R0)*(Q) - (Q+P)*((M(t))/((V-Q)*t));

% Implement Euler's method

for n=1:length(t)-1

M(n+1) = M(n) + f(t(n),M(n))*h;

end

% Plot the solution

plot(t,M/V), ylim([0,35]), grid('on')

title('Dilution of sea water')

xlabel('Time (h)'), ylabel('Salt concentration (g/L)')

However I get the following error:

Array indices must be positive integers or logical values.

Error in seawater>@(t,M)(R*(sin((pi*t)/12))^4+R0)*(Q)-(Q+P)*((M(t))/((V-Q)*t)) (line 13)

f = @(t,M) (R*(sin((pi*t)/12))^4 + R0)*(Q) - (Q+P)*((M(t))/((V-Q)*t));

Error in seawater (line 17)

M(n+1) = M(n) + f(t(n),M(n))*h;

Answer 1

[madhan ravi]

In line f, M(t) causes the error perhaps you mean‘t M*t ?

[Dex Feliciano]

Heres my question/

For part a I got the equation I stated earlier. It features a function M(t), which I dont know how to implement into MATLAB.

[Dex Feliciano]

Heres the equation I had at the end of question 4a. My differential equation.

The problem is in my M(t). My M is not a function in MATLAB so it can't take t as input variables. My M is a vector.

I just dont know how to factor in the M(t) part when entering my equation?