Suppose I have a function which has, say 5 inputs: say f(z,t1,t2,t3,t4). I want to do optimization using lsqnolin, i.e. min f(z,t1,t2,t3,t4). However, I have the following request:
User can determine which variables t1,t2,t3,t4 to be optimized. When user input 3 to the program, it means that I need to fix t4 while z,t1,t2,t3 can be changed to get the minimum value. If user input 2 to the program, it means that I need to fix t3,t4 while z,t1,t2 can be changed to get the minimum value.
I understand I can use conditional statement, but in my program, the function can have 20 inputs or even more. What's more, my program accept input [z,t1,t2,t3,t4] at the same time. What I find online require optimization of variables [z,t1,t2,t3,t4] at the same time, but not a particular variable to be fixed.
Related
I am working on an evacuation process project and would like to know if its possible to acquire a dataset for text or a variable from main and run in parameter variation experiment (for 100 runs) while storing/saving it after every iteration. This text keeps changing every time the simulation runs because the number of people able to escape during evacuation is different. An alarm (event) goes off and it triggers another event (event1), this then updates the text that counts the number of people in the building.
stopCounting of type boolean is false and peopleRemaining of type long
getPeopleInsideCount() comes from my function
The code I tried using in After experiment run for parameter variation experiment is
iteration3++;
dataset2.add(iteration3,(double)Long.parseLong(root.text2.getText()));
I understand that this code is unable to read the text from the main as a dataset. I have run the simulation in main and the text updates while also noticing that the peopleRemaining variable follows the number in text. Maybe it is possible to obtain variable in a dataset?
please learn to use the AnyLogic help as well. There, you will learn that a Dataset object only stores numbers. Also, a text object has only text as a String. They are not compatible.
You will want to store your evacuation number in a variable of type Int, name it myEvacNumber. So in addition of showing it in your text, you must manually store it in that variable. Best do that at the end of your evacuation ;-)
Then in your experiment in the "after simulation run" codebox, you can access it and store it into your dataset using
dataset.add(root.myEvacNumber);
Note that this will store the value that was in that variable at the very end of each simulation run!
I want to get different solution every time I run minisat on the same problem. I can do that with using "rnd-seed" parameter of minisat. It simply randomize the variable selection so each time I can get different solution. Even though this parameter works perfectly on my machine (Ubuntu16) it does not work on gcloud (Google Cloud) running on Ubuntu machine.
I think I am missing a small part but I can not figure out what that is.
Note: I do not want to feed negotation of a solution to minisat to get different solution. I actually need to randomize the variable selection.
Edit: Let me explain why I need randomized solution. I solve lots of SAT problems and usually these SAT problems look like each other a lot. So, if I can not randomized variable selection, I get most of the time very similar solutions which I do not want. Therefore, I actually do not run minisat on the same problem.
Edit-2: #sascha wanted me to explain what I mean by "works" and "not works". When I run a cnf file on my PC, each time I get different solution. However, when I run the same cnf file on gcloud machine, I get always same solution.
The option -rnd-seed doesn't randomize branch variable selection. Rather, it allows you to set a seed for the pseudo-random number generator that Minisat uses.
Variable selection for branching does not involve randomness unless the -rnd-freq option is used. Pass in a floating point value between 0 and 1. 0 means no randomness, 1 means try to use a random variable every branch. The code only makes one attempt to choose a variable randomly, presumably because searching for an unset variable in an arbitrarily large priority queue can get pretty expensive. If that one attempt fails, Minisat branches using the normal priority queue.
I have to work with a lot of data and run the same MATLAB program more than once, and every time the program is run it will store the data in the same preset variables. The problem is, every time the program is run the values are overwritten and replaced, most likely because all the variables are type double and are not a matrix. I know how to make a variable that can store multiple values in a program, but only when the program is run once.
This is the code I am able to provide:
volED = reconstructVolume(maskAlignedED1,maskAlignedED2,maskAlignedED3,res)
volMean = (volED1+volED2+volES3)/3
strokeVol = volED-volES
EF = strokeVol/volED*100
The program I am running depends on a ton more MATLAB files that I cannot provide at this moment, however I believe the double variables strokeVol and EF are created at this instant. How do I create a variable that will store multiple values and keep adding the values every time the program is run?
The reason your variables are "overwritten" with each run is that every function (or standalone program) has its own workspace where the local variables are located, and these local variables cease to exist when the function (or standalone program) returns/terminates. In order to preserve the value of a variable, you have to return it from your function. Since MATLAB passes its variables by value (rather than reference), you have to explicitly provide a vector (or more generally, an array) as input and output from your function if you want to have a cumulative set of data in your calling workspace. But it all depends on whether you have a function or a deployed program.
Assuming your program is a function
If your function is now declared as something like
function strokefraction(inputvars)
you can change its definition to
function [EFvec]=strokefraction(inputvars,EFvec)
%... code here ...
%volES initialized somewhere
volED = reconstructVolume(maskAlignedED1,maskAlignedED2,maskAlignedED3,res);
volMean = (volED1+volED2+volES3)/3;
strokeVol = volED-volES;
EF = strokeVol/volED*100;
EFvec = [EFvec; EF]; %add EF to output (column) vector
Note that it's legal to have the same name for an input and an output variable. Now, when you call your function (from MATLAB or from another function) each time, you add the vector to its call, like this:
EFvec=[]; %initialize with empty vector
for k=1:ndata %simulate several calls
inputvar=inputvarvector(k); %meaning that the input changes
EFvec=strokefraction(inputvar,EFvec);
end
and you will see that the size of EFvec grows from call to call, saving the output from each run. If you want to save several variables or arrays, do the same (for arrays, you can always introduce an input/output array with one more dimension for this purpose, but you probably have to use explicit indexing instead of just shoving the next EF value to the bottom of your vector).
Note that if your input/output array eventually grows large, then it will cost you a lot of time to keep allocating the necessary memory by small chunks. You could then choose to allocate the EFvec (or equivalent) array instead of initializing it to [], and introduce a counter variable telling you where to overwrite the next data points.
Disclaimer: what I said about the workspace of functions is only true for local variables. You could also define a global EFvec in your function and on your workspace, and then you don't have to pass it in and out of the function. As I haven't yet seen a problem which actually needed the use of global variables, I would avoid this option. Then you also have persistent variables, which are basically globals with their scope limited to their own workspace (run help global and help persistent in MATLAB if you'd like to know more, these help pages are surprisingly informative compared to usual help entries).
Assuming your program is a standalone (deployed) program
While I don't have any experience with standalone MATLAB programs, it seems to me that it would be hard to do what you want for that. A MathWorks Support answer suggests that you can pass variables to standalone programs, but only as you would pass to a shell script. By this I mean that you have to pass filenames or explicit numbers (but this makes sense, as there is no MATLAB workspace in the first place). This implies that in order to keep a cumulative set of output from your program you would probably have to store those in a file. This might not be so painful: opening a file to append the next set of data is straightforward (I don't know about issues such as efficiency, and anyway this all depends on how much data and how many runs of your function we're talking about).
I've been having a lot of trouble getting simulink's block callbacks to run, and the documentation is woefully inadequate and disorganized. It seems that I'm misunderstanding multiple points of how Simulink compiles models, but since StackOverflow dislikes multi-part questions, I will post them one at a time.
The situation: I have a library of components, each of which is a virtual subsystem whose parameters are defined through the masks. Block A has Parameter a which is sent to the base workspace using the 'assignin' command.
Next, the block B has a parameter b which is initialized in the Initialization tab of the mask.
Finally, the StartFcn callback of the block B runs a script which needs to reference both a and b to calculate c. In the script, I reference a simply as a because it's in the 'base' workspace, and I reference b using get_param(gcb,'b').
Now, this last command works when the parameter b is a user input (so it's a constant value). But in my case, this b is calculated using other parameters in the Initialization tab. And for some reason, in the script, this parameter is always zero.
I added a display within the block B to see what these values are, and they are clearly non-zero.
Can someone please explain why the script cannot seem to get the real value of the areas out of the block?
You can get the masked workspace variable using getworkspacevariable
I am currently working on a tool written in M-Script that executes a set of checks on a given simulink model. This tool does not compile/execute the model, I'm using find_system and get_param to retrieve all the information I need in order to run the routines of my tool.
I've reached a point where I need to determine whether a certain block has direct-feedthrough or not. I am not entirely sure how to do this. Two possible solutions come to mind:
A property might store this information and might be accessible via get_param. After investigating this, I could not find any such property.
Some block types have direct-feedthrough (Sum, Logic, ...), some other do not (Unit Delay, Integrator), so I could use the block type to determine whether a block has direct-feedthrough or not. Since I'm not an experienced Simulink modeller, I'm not sure if its possible to tell whether a block has direct-feedthrough by solely looking at its block type. Also, this would require a lookup table including all Simulink block types. An impossible task, since additional block types might get added to Simulink via third party modules.
Any help or pointers to possible solutions are greatly appreciated.
after some further research...
There is an "official solution" by Matlab:
just download the linked m-file
It shows that my idea was not that bad ;)
and for the record, my idea:
I think it's doable quite easily. I cannot present you some code yet, but I'll see what I can do. My idea is the following:
programatically create a new model
Add a Constant source block and a Terminator
add the Block you want to get to know the direct feedthrough ability in the middle
add_lines
run the simulation and log the states, which will give you the xout variable in the workspace.
If there is direct feedthrough the vector is empty, otherwise not.
probably you need to include some try/catch error catching for special cases
This way you can analyse a block for direct feedthrough by just migrating it to another model, without compiling your actual main model. It's not the fastest solution, but I can not imagine that performance matters that much for you.
Here we go, this script works fine for my examples:
function feedthrough = hasfeedthrough( input )
% get block path
blockinfo = find_system('simulink','Name',input);
blockpath = blockinfo{1};
% create new system
new_system('feed');
open_system('feed');
% add test model elements
src = add_block('simulink/Sources/Constant','feed/Constant');
src_ports = get_param(src,'PortHandles');
src_out = src_ports.Outport;
dest = add_block('simulink/Sinks/To Workspace','feed/simout');
dest_ports = get_param(dest,'PortHandles');
dest_in = dest_ports.Inport;
test = add_block(blockpath,'feed/test');
test_ports = get_param(test,'PortHandles');
test_in = test_ports.Inport;
test_out = test_ports.Outport;
add_line('feed',src_out,test_in);
add_line('feed',test_out,dest_in);
% setup simulation
set_param('feed','StopTime','0.1');
set_param('feed','Solver','ode3');
set_param('feed','FixedStep','0.05');
set_param('feed','SaveState','on');
% run simulation and get states
sim('feed');
% if condition for blocks like state space
feedthrough = isempty(xout);
if ~feedthrough
a = simout.data;
if ~any(a == xout);
feedthrough = ~feedthrough;
end
end
delete system
close_system('feed',1)
delete('feed');
end
When enter for example 'Gain' it will return 1, when you enter 'Integrator' it will return 0.
Execution time on my ancient machine is 1.3sec, not that bad.
Things you probably still have to do:
add another parameter, to define whether the block is continuous or discrete time and set the solver accordingly.
test some "extraordinary" blocks, maybe it's not working for everything. Also I haven implemented anything which could deal with logic, but actually the constant is 1 so it should work as well.
Just try out everything, at least it's a good base for you to work on.
A famous exception is the StateSpace Block which can have direct feedthrough AND states. But there are not sooo much standard blocks with this "behaviour". If you also have to deal with third party blocks you could get into some trouble, I have to admit that.
possible solution for the state space: if one compares xout with yout than one can find another indicator for direct feedthrough: if there is, the vectors are not equal. If so, than they are equal. Just an example, but I can imagine that it is possible to find more general ways to test things like that.
besides the added simout block above one needs the condition:
% if condition for blocks like state space
feedthrough = isempty(xout);
if ~feedthrough
a = simout.data;
if ~any(a == xout);
feedthrough = ~feedthrough;
end
end
From the documentation:
Tip
To determine if a block has direct feedthrough:
Double-click the
block. The block parameter dialog box opens.
Click the Help button in
the block parameter dialog box. The block reference page opens.
Scroll
to the Characteristics section of the block reference page, which
lists whether or not that block has direct feedthrough.
I couldn't find a programmatic equivalent though...
Based on a similar approach to the one by #thewaywewalk, you could set up a temporary model that contains an algebraic loop, similar to,
(Note that you would replace the State-Space block with any block that you want to test.)
Then set the diagnostics to error out if there is an algebraic loop,
If an error occurs when the model is compiled
>> modelname([],[],[],'compile');
(and you should check that it is the Algebraic Loop error that has occured), then the block has direct feed though.
If no error occurs then the block does not have direct feed though.
At this point you would need to terminate the model using
>> modelname([],[],[],'term');
If the block has multiple inports or outprts then you'll need to iterate over all combinations of them.