Please could someone explain the basics of how MATLAB updates codes in a script?

I'm kind of teaching myself how to use MATLAB and I try to write my codes like I would do on paper but it does not work out as I expect. For example, a code below:

spikeMat is a vector that has the values of either 0 or 1. I generated this using a function that I created

I am trying to say that anytime spikeMat(t) = 1, then fac_P(t) at timepoint t should increase by this formula: fac_P(t)= fac_P(t)+ (0.1 * ( 1 - fac_P(t))).

Then fac_P(t+1) should be :

fac_P(t+1)= facResting_P0 + ((fac_P(t)- facResting_P0) * exp(-dTime/fac_timeConst));

After this, the value of fac_P should not change till the next time spikeMat(t) = 1

dTime = 10^-3;
time = 0: dTime: 1;
fac_P = zeros(1, length(time));
fac_P(1) = 0;
facResting_P0 = 0;
fac_timeConst= 0.1;
for t = 1: length(time)-1
    [spikeMat] = poissonSpikeGen(10^-3, 100, 1, 1); %a function that I created elsewhere
    t_spike = find( spikeMat== 1);
    if ismember(t, t_spike)
        fac_P(t)= fac_P(t)+ (0.1 * ( 1 - fac_P(t)));
        fac_P(t+1)= facResting_P0 + ((fac_P(t)- facResting_P0) * exp(-dTime/fac_timeConst));
    end
    fac_P(t + 1) =  fac_P(t);
end

Answer 1

[Bob Thompson]

Did you delete and repost this question? I swear I saw it earlier today.

A couple of things about your code.

1) It doesn't look like you need to calculate spikeMat inside the for loop, because none of the inputs for your function involve t so the results will be the same every time you run the function. Keeping it inside the loop is just a waste of time.

2) Does spikeMat have an element that corresponds to every t? If so, you can replace some stuff.

% Original
t_spike = find(spikeMat == 1);
if ismember(t, t_spike)
    
% Replacement
if spikeMat(t) == 1

3) Inside your if condition you define a new value for fac_P(t) and fac_P(t+1), but outside your if statement you define fac_P(t+1). This means that even if you do change fac_P(t+1) inside the if, it will always be overwritten by the command which follows. I would suggest putting the second fac_P(t+1) command in an 'else' condition.

    if spikeMat(t) == 1
        fac_P(t)= fac_P(t)+ (0.1 * ( 1 - fac_P(t)));
        fac_P(t+1)= facResting_P0 + ((fac_P(t)- facResting_P0) * exp(-dTime/fac_timeConst));
    else
        fac_P(t + 1) =  fac_P(t);
    end

4) Do you know how to put debug markers in your code? I find that they are generally the best tool to make sure your if statements are triggering correctly.

[Temi O]

Thank you very much!