I would like to partially solve a MIP, clone the problem and have that copy of the problem continue optimization but with a different strategy (node selection rule, variable selection rule, etc), and keeping the current branch-and-bound tree. I know that this can't be done with either CPLEX or Gurobi, since they would start optimization from scratch in the copy.
Is there any way of doing this with SCIP?
I would really appreciate any help.
Best,
Rodolfo
If you don't insist on having a copy/clone, you always have the possibility to code your stopping criterion in terms of an event handler. I am sure you know our How to on adding event handlers.
There is also an event handler in the scip source code, the so-called soft time limit event handler src/scip/event_softtimelimit.c. There you can find sample code that changes the time limit after the first solution has been found. Parameters can be fed one by one by using the SCIPchg{Real,Bool,Int,Longint,Char,String}Param() methods in the code, or passed as a settings file, which might be easier if you want to change lots of parameters without adapting the code each time.
It is good practice to use settings files saved via the set diffsave command, which saves only the nondefault-settings. Otherwise, using a complete settings file, you might run into troubles because a time limit or memory limit gets changed without control.
A copy that includes data structures such as the tree used during the branch-and-bound solving process is currently not possible. The copy-mechanism of SCIP only allows to copy the problem as a whole and adjust the formulation by changing variable domains and/or objective coefficients.
Related
My Labview Program works like a charm, until I look at the Block Diagram. No changes are made. I do not Save. Just Ctrl+E and then Ctrl+R.
Now it does not work properly. Only a Restart of Labview fixes the problem.
My Program controls two Scanner arrays for Laser Cutting simultaneously. To force parallel working, I use the Error handler and loops that wait for a signal from the Scanner. But suddenly some loops run more often than they should.
What does majorly happen in Labview when I open the Block diagram that messes with my code?
Edit:
Its hard to tell what is happening without violating my non-disclosure agreement.
I'm controlling two independent mirror-Arrays for Laser Cutting. While one is running one Cutting-Job, the other is supposed to run the other Jobs. Just very fast. When the first is finished they meet at the same position and run the same geometry at the same slow speed. The jobs are provided as *.XML and stored as .net Objects. The device only runs the most recent job and overwrites it when getting a new one.
I can check if a job is still running. While this is true I run a while loop for the other jobs. Now this loop runs a few times too often and even ignores WAIT-blocks to a degree. Also it skips the part where it reads the XML job file, changes the speed part back to fast again and saves it. It only runs one time fast.
#Joe: No it does not. It only runs once well. afterwards it does not.
Youtube links
The way it is supposed to move
The wrong way
There is exactly one thing I can think of that changes solely by opening the block diagram.
When the block diagram opens, any commented-out or unreachable-code-compiler-eliminated sections of code will load their subVIs. If one of those commented out sections of code were somehow interfere with your running code, you might have an issue.
There are only two ways I know of for that to interfere... both of them are fairly improbable.
a) You have some sort of "check for all VIs in memory" or "check for all types in memory" that you're using as a plug-in system. When the commented-out sections load, that would change the VIs in memory. Such systems are not uncommon when parsing XML, so maybe.
b) You are using Run VI method for some dynamically invoked VI to execute as a top-level VI, but by loading the diagram, it discovers that it is a subVI of your current program. A VI cannot simultaneously be top-level and a subVI, so the call to Run VI returns an error.
That's it. I can't think of anything else. Both ideas seem unlikely, but given your claim and a lack of a block diagram, I figured I'd post it as a hypothesis.
In the improbable case someone has a similar problem. The problem was a xml file that was read during run time. Sometimes multiple instances tried to access it and this produced the error.
Quick point to check: are Debug and "retain data in wires" disabled? While it may not change the computations, but it may certainly change the timing of very tight loops, and that was one of the unexpected program behaviors, OP was referring to.
I was wondering if there were a way to compute the size of a reg in Verilog. I researched it quite a bit, and found $size(a), but it's only in SystemVerilog, and it won't work in my verilog program.
Does anyone know an alternative for this??
I also wanted to ask as a side note; I'm having some trouble with my test bench in the sense that when I update a value in the file, that change is not taken in consideration when I simulate. I've been told I might have been using an old test bench but the one I am continuously simulating is the only one available in this project.
EDIT:
To give you an idea of what's the problem: in my code there is a "start" signal and when it is set to 1, the operation starts. Otherwise, it stays idle. I began writing the test bench with start=0, tested it and simulated it, then edited the test bench by setting start to 1. But when I simulate it, the start signal remains 0 in the waveform. I tried to check whether I was using another test bench, but it is the only test bench I am using in this project.
Given that I was on a deadline, I worked on the code so that it would adapt to the "frozen" test bench. I am getting now all the results I want, but I wanted to test some other features of my code, so I created a new project and copy pasted the code in new files (including the same test bench). But when I ran a simulation, the waveform displayed wrong results (even though I was using the exact same code in all modules and test bench). Any idea why?
Any help would be appreciated :)
There is a standardised way to do this, but it requires you to use the VPI, which I don't think you get on Modelsim's student edition. In short, you have to write C code, and dynamically link it to the simulator. In the C code, you can get object properties using routines such as vpi_get. Useful properites might be vpiSize, which is what you want, vpiLeftRange, vpiRightRange, and so on.
Having said all that, Verilog is essentially a static language, and objects have to be declared with a static width using constant expressions. Having a run-time method to determine an object's size is therefore of pretty limited value (since you should already know it), and may not solve whatever problem you actually have. Your question would make more sense for VHDL (and SystemVerilog?), which are much more dynamic.
Note on Icarus: the developers have pushed lots of SystemVerilog stuff back into the main language. If you take advantge of this you may find that your code is not portable.
Second part of your question: you need to be specific on what your problem actually is.
I'm trying to pass data which is continuously changed from the inside of one While loop to the inside of another While loop of a sub-vi. The main program on the left is constantly reading new data and the program on the right is adding 1 to the new value. My issue is that I cannot input new values to a While loop which is already running and thus my sub-vi is never updated. I've tried a global variable ("write" from the main program control and then "read" into the sub-vi) but that doesn't work either (same result as if the main were just passing data into the sub).
I apparently don't have enough reputation to post a picture of my program but I'm basically trying to run parallel loops (almost inside each other). Can anyone lend me an experienced hand?
The most common problem with while loops are based on lack of knowledge how exactly does the while loop work in LabVIEW.
First of all the information will be given outside the loop only if the condition terminal (right down corner of the loop) will be flagged as true.
If you want to pass the data earlier (while the loop is running) you have to choose easiest option:
Use queue (is the most common and well working). I can elaborate how this one work in practise if you want, or just try to run an example from LabVIEW help.
local/shared variables - you can define in your own library variables and pass the data by READ/WRITE option.
Please try to upload some documentation to an external server (as you are blocked here), and post a link, and then I could help you with a specific example.
Help»Find Examples. Search for "queue". Pick out an example with parallel loops.
You might want to look into Queues or Notifiers as means of passing data between running loops.
is there any way to use html anchor tag in a gml file..I want to create a hyperlink to location/point in a gml file.
how can i do so???
thanks in advance..
This is a little known GML technique that GREATLY increases the power of Game Maker, and is well worth learning, but as a note, it does NOT work in Studio, because of the countless new restrictions on commands. Go back to GM8.1 (I only ever use that now), and you should have no problem making use of this technique.
The technique is to write a program in another language through GML (batch, vbs, etc, or in this case, HTLM), execute it through GML, then delete the program.
Quite simply, use the file_text commands to create a file with the correct content and extension, execute it with execute_program, and then delete it with file_delete.
Specifically for this script:
argument0 is the link, including the protocol.
argument1 is the anchor, minus the # (that's handled for you).
argument2 is the full browser path.
argument3 is important. This is the time in milliseconds the program will wait before deleting the temporary link file.
(The execute_program command, even when told to wait for the program to complete, continues as soon as the temp file is loaded. If external, the redirect takes some time depending on your connection, so deleting the temporary file halfway through will cause it to fail. 10 milliseconds worked fine for me. The program will hang for this time in this setup, but if you would like to set up an alarm based system to stop it from hanging, that wouldn't be too hard.)
In other uses of this technique without the use of the internet (I use small batch and vbs files a lot), the "hang time" (pun not intended) is usually not necessary.
In addition, the browser location will need to be changed for each different computer
file=file_text_open_write(temp_directory+"\tempLink.html")
file_text_write_string(file,'<!DOCTYPE html>')
file_text_writeln(file)
file_text_write_string(file,'<html>')
file_text_writeln(file)
file_text_write_string(file,'<body onload="')
file_text_write_string(file,"location.href='")
file_text_write_string(file,argument0+"#"+argument1+"';")
file_text_write_string(file,'">')
file_text_writeln(file)
file_text_write_string(file,'</body>')
file_text_writeln(file)
file_text_write_string(file,'</html>')
file_text_close(file)
execute_program(argument2,temp_directory+"\tempLink.html",true)
sleep(argument3)
file_delete(temp_directory+"\tempLink.html")
Sorry I wish It was possible but it's not unless you want to spend a lot of time with dll's. BUT you can create a Script and reuse it everywhere in your code...
script0(argument0,argument1...)
I found the Wikipedia entry on the soft coding anti-pattern terse and confusing. So what is soft coding? In what settings is it a bad practice (anti-pattern)? Also, when could it be considered beneficial, and if so, how should it be implemented?
Short answer: Going to extremes to avoid Hard Coding and ending up with some monster convoluted abstraction layer to maintain that is worse than if the hard coded values had been there from the start. i.e. over engineering.
Like:
SpecialFileClass file = new SpecialFileClass( 200 ); // hard coded
SpecialFileClass file = new SpecialFileClass( DBConfig.Start().GetConnection().LookupValue("MaxBufferSizeOfSpecialFile").GetValue());
The main point of the Daily WTF article on soft coding is that because of premature optimization and fear a system that is very well defined and there is no duplicated knowledge is altered and becomes more complex without any need.
The main thing that you should keep in mind is if your changes actually improve your system and avoid to lightly label something as anti-pattern and avoid it by all means. Configuring your system and avoiding hardcoding is a simple cure for duplicated knowledge in your system (see point 11 : "DRY Don't Repeat Yourself" in The Pragmatic Programmer Quick Reference Guide) This is the driving need behind the suggestion of avoiding hardcoding. I.e. there should be ideally only one place in you system (that would be code or configuration) that should be altered if you have to change something as simple as an error message.
Ola, a good example of a real project that has the concept of softcoding built in to it is the Django project. Their settings.py file abstracts certain data settings so that you can make the changes there instead of embedding them within your code. You can also add values to that file if necessary and use them where necessary.
http://docs.djangoproject.com/en/dev/topics/settings/
Example:
This could be a snippet from the settings.py file:
num_rows = 20
Then within one of your files you could access that value:
from django.conf import settings
...
for x in xrange(settings.num_rows):
...
Soft-coding: it is process of inserting values from external source into computer program. like insert values through keyboard, command line interface. Soft-coding considered as good programming practice because developers can easily modify programs.
Hard-coding. Assign values to program during writing source code and make executable file of program.Now, it is very difficult process to change or modify the program source code values. like in block-chain technology, genesis block is hard-code that cannot changed or modified.
The ultimate in softcoding:
const float pi = 3.1415; // Don't want to hardcode this everywhere in case we ever need to ship to Indiana.