I have a model in matlab simulink .I want to measure the time when a signal is received in the simulink model .Is there any way to find the time .Appreciate if someone could share your knowledge on this .
I could not find any solution for this
In order to get the time that took to your Matlab commands you can use Matlab's tic & toc commands.
Add tic command before the code and toc after the code and you will get the time
Example from mathworks site:
tic
A = rand(12000,4400);
B = rand(12000,4400);
toc
It will print:
Elapsed time is 0.664779 seconds.
Related
I have a simulation which will run for several hours in Simulink. Is it possible to detect see total duration of simulation in Matlab or Simulink?
tic/toc does this. tic starts the timer, toc ends it. Time is given in seconds, adjust according to your needs.
tic
% code here
time = toc;
frpintf('It took %f s',time)
I am able to find similar answer of C/C++ in the following question:
Fast implementation/approximation of pow() function in C/C++
My code's bottleneck as per profiler is something similar to following code:
a=rand(100,1); % a is an array of doubles
b=1.2; % power can be double instead of only integers.
temp=power(a,b); % this line is taking maximum time
For my requirement, only first 3-4 digits are significant, so any fast approximation of power will be very useful to me. Any suggestions to do the same.
More Information:
this is how I calculated power using exp and log. This has improvement of roughly 50%. Now I need to find approx functions of log and exp and check if that is faster still.
a=rand(1000,1);
tic;
for i=1:100000
powA=power(a,1.1);
end
toc;
tic;
for i=1:100000
powB=exp(1.1*log(a));
end
toc;
Elapsed time is 4.098334 seconds.
Elapsed time is 1.994894 seconds.
i confront with a weird fact! i wrote a matlab code that compare runing time of two algorithms. i embrace codes of each algorithm by tic toc functions, so i can compare time complexities of them. but weird thing is here:
if i run the script at once, algorithm 1 has longer time than algorithm 2, but if i put breakmarks after each toc, algorithm 1 would has shorter time!
in order to understand better what I said, consider following:
tic
% some matlab codes implementing algorithm1
time1 = toc;
disp(['t1 = ',num2str(time1)]) % here is the place for first breakpoint
tic
% some matlab codes implementing algorithm2
time2 = toc;
disp(['t2 = ',num2str(time2)]) % here is the place for second breakpoint
can anyone please explain to me why this happen? thanks
I am using global optimization toolbox to run genetic algorithm on Matlab. However, I do not see any documentation or function to record the CPU time.
You can use the function cputime explained here. It returns time in seconds. Although, tic and toc are a better choice for measuring performance in Matlab codes.
A sample code :
startTime = cputime;
% GA Code
endTime = cputime;
cpu_time_consumed = endTime - startTime;
I realized that this can also be done using the "Run and Time" option available in Matlab.
I am working with loops.I am using tic toc to check the time. I get different time when i run the same loop. The time is close to each other eg. 98.2 and 97.7. secondly when i reduce the size of the loop to half, i expect the time to change in half but it doesn't. Can anyone explain me how tic toc actually works?
Thanks.
tic
for i=1:124
for j=1:10
for k=1:11
end
end
end
toc
Secondly i tried to use tic toc inside the loop as shown below. Will it return total time? I get a number but i cant verify if it actually is the total.
for i=1:124
tic
for j=1:10
for k=1:11
end
end
toc
end
tic and toc just measure the elapsed time in seconds. MATLAB has now JIT meaning that the actual time to compute cannot be estimated correctly.
Matlab has (at least in this context) no real-time computation, so you basically always have different elapsed time for the same code.
Read this here, its nicely explained, hopefully it helps: http://www.matlabtips.com/matlab-is-no-longer-slow-at-for-loops/