MATLAB Answers

no output when coding

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Boss Man
Boss Man 10 Feb 2020
편집: Adam Danz 14 May 2020 17:25
a = xlsread('outdoorall.xlsx','H2:H52364');
b=xlsread('indoorall.xlsx','H2:H52364'); %2397
t=xlsread('outdoorall.xlsx','E2:E52364');% time in secs
for i=1:2363
dti=t(i+1)-t(i);
dt=(b(i+1)-b(i))/dti; % change in indoor temperature divided by time
c=dt/a(i)-b(i);
plot(c)
end
the idea is each time step is different so i want to divide the change in temp by each unique time step

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Boss Man
Boss Man 11 Feb 2020
still no plot
aim is to work out the difference between each time interval then divide the subsequent difference from dt to produce a graph
Adam Danz
Adam Danz 11 Feb 2020
Copy of question
a = xlsread('outdoorall.xlsx','H2:H52364');
b=xlsread('indoorall.xlsx','H2:H52364'); %2397
t=xlsread('outdoorall.xlsx','E2:E52364');% time in secs
for i=1:2363
dti=t(i+1)-t(i);
dt=(b(i+1)-b(i))/dti; % change in indoor temperature divided by time
c=dt/a(i)-b(i);
plot(c)
end
the idea is each time step is different so i want to divide the change in temp by each unique time step
___________________________________________________________
My comment
Try
c = nan(1, 2363);
for i=1:2363
dti=t(i+1)-t(i);
dt=(b(i+1)-b(i))/dti; % change in indoor temperature divided by time
c(i)=dt/a(i)-b(i);
end
plot(c)
or
hold on
for i=1:2363
dti=t(i+1)-t(i);
dt=(b(i+1)-b(i))/dti; % change in indoor temperature divided by time
c=dt/a(i)-b(i);
plot(c, 'o')
end
Rena Berman
Rena Berman 14 May 2020 17:05
(Answers Dev) Restored edit

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Henry Gotjen
Henry Gotjen 11 Feb 2020
편집: Henry Gotjen 11 Feb 2020
Do this without a for loop
% Load data
a = xlsread('outdoorall.xlsx','H2:H52364');
b=xlsread('indoorall.xlsx','H2:H52364'); %2397
t=xlsread('outdoorall.xlsx','E2:E52364');% time in secs
a = a(:); b = b(:); t = t(:); % make sure we're working with column vectors
dti = diff(t) % difference between each value of t, length is one less than 1;
% it looks like your formula is the difference in db/dt divided by the difference between a and b.
% Pad db/dt with 0 so the array length matches with a and b.
c = [0; diff(b)./dt] ./ (a-b) ;
plot(t,c)
is this what you're trying to do?

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Boss Man
Boss Man 11 Feb 2020
I'm a bit confused now, this is the eq i'm trying to solve.
I need it to be consecutive values so i dont think rand would be useful to me.
so which of these codes would work?
Also why is it to end-1 and not end?
Stephen Cobeldick
Stephen Cobeldick 11 Feb 2020
"I need it to be consecutive values so i dont think rand would be useful to me."
You did not provide a, b, or t, so Adam Danz quite reasonably just used some matrices of random values in order to actually run the code on something.
You should use your own arrays, of course, not the random values that are just used for testing.
Boss Man
Boss Man 11 Feb 2020
apologies, thought i attached the data

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