help w code error

%Euler's Method
p = 1;  
t = 0:p:100;  
S = zeros(size(t));  
S(1) = 1.000;  %initial concentration 
n = numel(S);  %number of y values (S is y in this case) 
disp('   Time      Reactant Concentration  ')
disp('   (sec)           (mol/L)  ')
disp('   --------------------------------  ')
%loop to solve the eq
for i=1:n-1
    f = -0.5 /(2.1+S)
    S(i+1) = S(i) + p * f; %eulers formula
    fprintf('6.0f%15.3f\n',t(i), S(i))
end

i am receiving an error for the f = -0.5 /(2.1+S) it says "Error using / Matrix dimensions must agree."

[madhan ravi]

Why ask a question if you’re so concerned? Why waste others time?

[Rik]

Comment posted as flag by Paige Macdonald:

i dont want this question posted anymore

[Rik]

That is not an answer to the question Madhan posted. You got free help from a stranger on the internet. Why did you decide to remove your question? You could have simply not posted it. Now you are an inconsiderate jerk taking advantage of friendly people. Is that your intent?

[Rik]

Original question as posted by Paige Macdonald, retrieved from Google cache (permalink):

%Euler's Method
p = 1;  
t = 0:p:100;  
S = zeros(size(t));  
S(1) = 1.000;  %initial concentration 
n = numel(S);  %number of y values (S is y in this case) 
disp('   Time      Reactant Concentration  ')
disp('   (sec)           (mol/L)  ')
disp('   --------------------------------  ')
%loop to solve the eq
for i=1:n-1
    f = -0.5 /(2.1+S)
    S(i+1) = S(i) + p * f; %eulers formula
    fprintf('6.0f%15.3f\n',t(i), S(i))
end

i am receiving an error for the f = -0.5 /(2.1+S) it says "Error using / Matrix dimensions must agree."

[Rena Berman]

(Answers Dev) Restored edit

[Rik]

Why did you edit your question again? I will simply revert your edit again. If you want it removed, contact Mathworks. Unless and until I hear from them to leave your edit, I will be reverting it every time you edit this. Why waste your time trying to see if you're more stubborn than me?

Answer 1

[James Tursa]

You need to index S:

f = -0.5 /(2.1+S(i));