Speed up MATLAB code

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP



Speed up MATLAB code



In my code, I have a line where I calculate the cumulative sum of a vector, A, using the cumsum() function in MATLAB (R2017b). However, between each iteration, only one element in the vector A changes, and so really it's only the values from that point onwards that change. I was wondering if there was a faster way of doing this? I have tried A(elementNumber:end) = A(elementNumber:end) - oldValue + newValue, but this isn't any faster.



Additionally, I then use the find() function at each iteration to find the first index in this cumulative sum matrix where the value first exceeds a certain value.



I was wondering if there was a faster way to perform either of these in MATLAB?



An example of the kind of code I am using is given below:


beta = 0.05;
S = randi(130, 15000, 1); I = randi(130, 15000, 1);
tmax = 10000; n=1; t(1) = 0; t1=0;
rates = (beta.*S.*I); cums = cumsum(rates); numI = sum(I);
Rtot = cums(end);
n=1; t(1) = 0; t1=0;
while t1<tmax
if n>1
newRate = beta*S(eventHouseNum)*I(eventHouseNum);
% rates(eventHouseNum) = beta*S(eventHouseNum)*I(eventHouseNum);
cums(eventHouseNum:end) = cums(eventHouseNum:end) - rates(eventHouseNum) + newRate;
rates(eventHouseNum) = newRate
end
Rtot = cums(end);
if Rtot==0
return
end
randNums = rand(2,1);
dt=-log(randNums(1))/Rtot;
P=randNums(2)*Rtot;
eventHouseNum = find(cums>=P,1);
S(eventHouseNum) = S(eventHouseNum)-1;
I(eventHouseNum) = S(eventHouseNum)+1;
numI = numI+1; n=n+1;
t(n)=t(n-1)+dt; t1=t(n);
Iarray1(n) = numI;
end





@Wolfie I've added a shortened example of the code. Is that okay, or is there still too much there?
– user112495
Aug 10 at 14:26






Profile your code, then check what makes it slow.
– Ander Biguri
Aug 10 at 15:05





@AnderBiguri I know it's definitely the cumsums and the finds that are taking up the majority of the time (along with generating the random numbers - but there's nothing I can do about that).
– user112495
Aug 10 at 15:12






@user112495 you can then probably produce a considerably smaller code for us to test
– Ander Biguri
Aug 10 at 15:14





@AnderBiguri I've produced something a bit simpler. In the above example, about 50% of the time is spent on cumsum(), and about 40% on find().
– user112495
Aug 10 at 15:35










By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

-

Popular posts from this blog

Firebase Auth - with Email and Password - Check user already registered

Image
Clash Royale CLAN TAG #URR8PPP Firebase Auth - with Email and Password - Check user already registered I want to check when a user attempts to signup with createUserWithEmailAndPassword() in Firebase user Authentication method, this user is already registered with my app. createUserWithEmailAndPassword() 8 Answers 8 To detect whether a user with that email address already exists, you can detect when the call to createUserWithEmailAndPassword () fails with auth/email-already-in-use . I see that @Srinivasan just posted an answer for this. createUserWithEmailAndPassword () auth/email-already-in-use Alternatively, you can detect that an email address is already used by calling fetchSignInMethodsForEmail() (previous called fetchProvidersForEmail() ). fetchSignInMethodsForEmail() fetchProvidersForEmail() When the user trying to create an user with same email address, the task response will be "Response: The email address is already in use by another account." mFirebas
Read more

Dynamically update html content plain JS

Image
Clash Royale CLAN TAG #URR8PPP Dynamically update html content plain JS So I have a script bound in my index.html, which literally has to fetch an array of jsons from an api, then dynamically update my page when get response. But as a result I'm getting an as the only update of my page. here is my script fetch(url) .then((resp) => resp.json()) .then((resp) => resp.results.forEach(item => fetch(item.url) .then((response)=> response.json()) .then((response) => pokeArr.push(response)) .catch(console.log) ) ).catch(console.log) const filler = () => if(!pokeArr) return 0 pokeArr.map((i,j)=> return `<tr>$i.name</tr>` ) const pokeindex = () => document.getElementById('a').appendChild(document.createElement(filler())) pokeindex() When I'm consoling it, I can see in the console all the responses I get, so I'm at least doing the fetching part right. What's parberakan ? What's pokeArr ? – T.J. Crowder Aug 8 at 12
Read more

Creating a leaderboard in HTML/JS

Image
Clash Royale CLAN TAG #URR8PPP Creating a leaderboard in HTML/JS I'm trying to create a top 10 leaderboard, for now, I've only implemented 3 players, but I'm coming across an issue. My script doesn't seem to be outputting anything on webpage. The purpose of the script is to compare 3 arrays, player1,player2,and player3 solely based off of score. Which is the 2nd index of each array. I want the script to list the players in order of highest score. This method doesn't really seem to be efficient, especially when I'll have to add 7 more players. Could someone suggest perhaps an easier approach, as well as show me why my script wont output the info. Here's the JS function leaderboard() { var player1 = name:"Thomas",date:"01/23/18",score:"201"; var player2 = name:"Michael",date:"03/24/17",score:"943"; var player3 = Name:"Lisa",date:"06/04/18",Score:"79"; if(player1[2]&g
Read more