Array indices must be positive integers or logical values

So i have the following Constraints for a heat storage (ws) as part of my yalmip optimization problem:

Constraints=[]
for t = 1:24
    Constraints = [Constraints, dE(t) <= dEmax_WS, E_ws(t) <= Emax_ws, E_ws(t) == E_ws(t-1)+dE(t), E_ws(0) == 10];
end

When running, i get an indexing error:

"Error using sdpvar/subsref (line 161) -Array indices must be positive integers or logical values."

I assume the problem is the last equation, which should determine the current state of charge by adding the charge rate to the charge of the previous time step.

I know one way to change this is to start the loop at t=2 and define E_ws(1)=10. Is there another smoother way which lets me keep the equation in the same loop as the "regular" constraints?

Thank you!

Answer 1

[KSSV]

This line:

E_ws(0) == 10

gives you error. MATLAB indexing starts from 1. It cannot be zero. Think of it.

[Fabian Haslwanter]

Hey @KSSV,

sorry, that part E(0)=10 was actually not supposed to be in there (was part of my trial and error). But without that line i still get the same error.

As mentioned in the last part of my post, i already managed to solve it by indexing E_ws(1)=10 and starting the loop at t=2. However this is really annoying and i am looking for a way to implement the condition together with the regular conditions in the same for loop.

Hope that somehow makes sense. Sorry for the misunderstanding and also the confusing way to ask the question.

[KSSV]

This line:

 E_ws(t) == E_ws(t-1)+dE(t)

t-1 will b3 0 when t = 1 in the loop.

[Fabian Haslwanter]

I tried this as well, but I am still getting the same error:

clear all
%Constraints
Constraints=[];

for t = 1:24
    Constraints = [Constraints, dE(t) <= dEmax_ws, E_ws(t) <= Emax_ws, E_ws(t) == E_ws(t-1)+dE(t)];
end

[Walter Roberson]

when t=1 then E_ws(t-1) is not a valid index