Why am I receiving multiple database errors for a simple line of code?

I've been trying to find the time a machine fails during a defined period. The latter is defined as the time difference between a 'False' true_false indicator and the following 'True' indicator. However, there is a limitation that if the time exceeds one day, 8 hours must be deducted (the time the virtual plant closes). This is an example of the tables I am analyzing labeled as ALPI01.

time state failure true_false

'PI01' '15.12.2022 13:09:29.784' 'state' 'PI01_Failed01' 'True'

'PI01' '15.12.2022 13:16:35.541' 'state' 'PI01_Failed01' 'False'

'PI01' '15.12.2022 13:37:33.189' 'state' 'PI01_Failed01' 'True'

'PI01' '15.12.2022 13:39:28.332' 'state' 'PI01_Failed01' 'False'

'PI01' '16.12.2022 11:34:29.726' 'state' 'PI01_Failed01' 'True'

'PI01' '16.12.2022 11:45:15.327' 'state' 'PI01_Failed01' 'False'

'PI01' '16.12.2022 19:43:42.487' 'state' 'PI01_Failed01' 'True'

'PI01' '16.12.2022 19:45:15.908' 'state' 'PI01_Failed01' 'False'

The code I wrote to serve my request is the following:

z =1;
 for i=1:size(ALPI01.time)
     if isequal(cell2mat(ALPI01.true_false(i)),'False')
         if day(ALPI01.time(i+1)) == day(ALPI01.time(i))
         FPI01(z) = seconds(ALPI01.time(i+1) - ALPI01.time(i));
         z = z+1;
         else 
             FPI01(z) = seconds(ALPI01.time(i+1) - ALPI01.time(i)) -28800;
             z = z +1; 
         end 
     end 
 end 
 

I used the day function before and it worked like a charm. I even used the same code but with few alterations to the repair time which is just the opposite of what I am finding now, and it worked pretty fine. Whenever I run this code I get the following error:

 Error in matlab.internal.datatypes.parenReference_1D (line 12)
    data = data(rowIndices);

Error in datetime/parenReference (line 19)
        obj.data = parenReference_1D(obj.data, rowIndices);

Error in tabular/dotParenReference (line 114)
        b = b(rowIndices);

Error in MTTF_MTTR1 (line 144)
         if day(ALPI01.time(i+1)) == day(ALPI01.time(i))
 

As you can notice I am a noob when it comes to MATLAB, but I am working on myself.

Any help or clarification would be appreciated!

Answer 1

[Bora Eryilmaz]

Your for loop index, i, goes up to

size(ALPI01.time)

and you are trying to index into the (i+1)th entry of the variable ALPI01.time within the for loop. When i == size(ALPI01.time) at the end of the for loop, the (i+1) entry of that variable does not exist in the expression:

if day(ALPI01.time(i+1)) == day(ALPI01.time(i))    

You can make your for loop go up to:

for i=1:size(ALPI01.time)-1
    

to fix the issue.

[Mike Jam]

Thank you so much!