Matlab, timed iteration over a matrix - arrays

I'm developing a simulator of sorts as a hobby project. The specific function i'm having trouble with takes a row from a matrix and supplies to a function every 50'th millisecond, but I'm a novice with Matlab scripting and need some help.
Each time the timer clicks, the next row in the matrix should be supplied to the function "simulate_datapoint()". Simulate_datapoint() takes the row, performs some calculation magic and updates a complex "track" object in the tracks array.
Is this a completely backwards way of trying to solve this problem or am I close to a working solution? Any help would be greatly appreciated.
Here's what I have right now that doesn't work:
function simulate_data(data)
if ~ismatrix(data)
error('Input must be a matrix.')
end
tracks = tracks_init(); % create an array of 64 Track objects.
data_size = size(data,1); % number of rows in data.
i = 0;
running = 1;
t = timer('StartDelay', 1, 'Period', 0.05, 'TasksToExecute', data_size, ...
'ExecutionMode', 'fixedRate');
t.StopFcn = 'running = 0;';
t.TimerFcn = 'i = i+1; simulate_datapoint(tracks, data(i,:));';
disp('Starting timer.')
start(t);
while(running==1)
% do nothing, wait for timer to finish.
end
delete(t);
disp('Execution complete.')
end

You're very close to a working prototype. A few notes.
1) Your string specified MATLAB functions for the timerFn and stopFn don't share the same memory address, so the variable "i" is meaningless and not shared across them
2) Use waitfor(myTimer) to wait... for the timer.
The following code should get you started, where I used "nested functions" which do share scope with the calling function, so they know about and share variables with the calling scope:
function simulate
iterCount = 0;
running = true;
t = timer('StartDelay', 1, 'Period', 0.05, 'TasksToExecute', 10, ...
'ExecutionMode', 'fixedRate');
t.StopFcn = #(source,event)myStopFn;
t.TimerFcn = #(source,event)myTimerFn;
disp('Starting timer.')
start(t);
waitfor(t);
delete(t);
disp('Execution complete.')
% These are NESTED functions, they have access to variables in the
% calling function's (simulate's) scope, like "iterCount"
% See: http://www.mathworks.com/help/matlab/matlab_prog/nested-functions.html
function myStopFn
running = false;
end
function myTimerFn
iterCount = iterCount + 1;
disp(iterCount);
end
end

Related

Loop help (roblox)

I have a problem with this script:
local plight = script.Parent.Bulb.PointLight
local slight = script.Parent.Bulb.SpotLight
local rotatingPart = script.Parent.Bulb
local reader = script.Parent.Parent["card-reader1a"].reader1a.ProximityPrompt
local c = 0
local cc = 0
local tweenService = game:GetService("TweenService")
local tInfo = TweenInfo.new(0.5, Enum.EasingStyle.Linear, Enum.EasingDirection.InOut, 0, false)
local function rotating()
if c == 0 then
c = 1
local play1 = tweenService:Create(rotatingPart, tInfo, {CFrame = rotatingPart.CFrame * CFrame.Angles(0, math.rad(120), 0)})
play1:Play()
play1.Completed:Connect(rotating)
c = 0
end
end
reader.Triggered:Connect(rotating)
I have infinitive loop and I don't know how to stop it. I tried many methods and nothing worked. Can someone help?
Try removing
play1.completed:Connect(rotating)
This line of code means that upon the tween's completion fire the rotating function. Effectively causing an infinite loop.
Additionally since :Connect() a signal doesn't yield, every time rotating is called, c is set from 1 to 0 almost instantaneously. Which allows all calls to pretty much bypass the debounce.
If you wish to wait until the tween is complete, try using
play1.completed:Wait()

iOS9 Beta and MusicTrackLoopInfo

Has anyone been able to loop a MIDI file without problems on IOS9 Beta?
As soon as I try to loop by setting numberOfLoops to 0 in MusicTrackLoopInfo, it locks up the app by sending random MIDI to the player. I've reported it, but am wondering if anyone has found a work around. The same code works perfectly under all other iOS versions.
MusicTrackLoopInfo loopInfo;
loopInfo.loopDuration = loopLength;
loopInfo.numberOfLoops = 0;
OK I just heard iOS9 will ship with this bug in it. Terrible.
Here is a work around.
Don't set numberOfLoops at all, OR set numberOfLoops = 1; // means loop once
Now make a variable (i.e. myVariableToKeepTrackOfAddedCopies) that keeps track of the number of times you will actually perform the following:
In your MIDIReadProc at some point BEFORE the track has finished playing, do the following:
// Copy the track to itself - effectively doubling the length
MusicTrack theTrack=nil;
MusicTrackGetProperty(theTrack, kSequenceTrackProperty_TrackLength, &trackLen, &trackLenLen);
trackLen = 4.0; //<-- this is your real track length
MusicTrackCopyInsert(theTrack, 0, trackLen, theTrack, 0);
myVariableToKeepTrackOfAddedCopies++;
So now your track is twice as long before it ends and the track will continue. This will work the same as looping except you are taking up more memory since you are making the track length longer after each iteration.
When you stop the sequence/track, cut the track back to the original size.
MusicTrackCut(theTrack, 4.0, 4.0 + (4.0*myVariableToKeepTrackOfAddedCopies));
MusicTrackGetProperty(theTrack, kSequenceTrackProperty_TrackLength, &trackLen, &trackLenLen);
Irritating, but it works. I just verified on iOS9 beta 5. Hope it helps.
This is fixed as of iOS release 9.2
Oddly enough, the tempo track does not seem to have this problem. The following code does not lock up for me:
MusicTrack tempoTrack;
OSSTATUS = MusicSequenceGetTempoTrack(self.sequence, &tempoTrack);
SafeMusicTrackClear(tempoTrack); //calls into MusicTrackClear
MusicTrackNewExtendedTempoEvent(tempoTrack, 0, self.tempo * self.tempoMultiplier);
MIDIMetaEvent timeSignatureMetaEvent;
timeSignatureMetaEvent.metaEventType = 0x58;
timeSignatureMetaEvent.dataLength = 4;
timeSignatureMetaEvent.data[0] = 1;
timeSignatureMetaEvent.data[1] = 4;
timeSignatureMetaEvent.data[2] = 0x18;
timeSignatureMetaEvent.data[3] = 0x08;
MusicTrackNewMetaEvent(tempoTrack, 0, &timeSignatureMetaEvent);
MusicTrackLoopInfo loopInfo;
loopInfo.loopDuration = 0.25f;
loopInfo.numberOfLoops = 0;
MusicTrackSetProperty(tempoTrack, kSequenceTrackProperty_LoopInfo, &loopInfo, sizeof(loopInfo));
Unfortunately, it does not seem that the tempo track can actually play notes.
UPDATE:
After a few hours of digging around and trying to figure out a better solution to the problem, I settled on manually looping by sending a user event at the end of my sequence.
My sequence is created in a method...
-(void) loadPacketsForLoopingSequence {
SafeMusicTrackClear(loopingTrack); //calls into MusicTrackClear
// calculate timestampToPlaySequenceAt -- the starting point of the current sequence iteration, probably in the past, based on MusicPlayerGetTime and the length of the sequence -- here
// calculate timestampToPlayNextSequenceAt -- the starting point of the next sequence iteration, based on MusicPlayerGetTime and the length of the sequence -- here
// a single iteration of the notes get added to loopingTrack here, starting at timestampToPlaySequenceAt
MusicEventUserData event;
event.length = 1;
event.data[0] = 0xab; //arbitrary designation
// -0.5 to make sure we still have time to do the next step in the callback
MusicTrackNewUserEvent(loopingTrack, timestampToPlayNextSequenceAt - 0.5, &event);
}
...which is called again in the callback:
void sequenceCallback(void* inClientData,
MusicSequence inSequence,
MusicTrack inTrack,
MusicTimeStamp inEventTime,
const MusicEventUserData* inEventData,
MusicTimeStamp inStartSliceBeat,
MusicTimeStamp inEndSliceBeat) {
CSMidiMusicPlayer* musicPlayer = (CSMidiMusicPlayer*)inClientData;
[musicPlayer loadPacketsForLoopingSequence];
}
The callback has to be registered during sequence init using MusicSequenceSetUserCallback.
The -0.5 kludge could probably be eliminated altogether by examining the parameters in sequenceCallback and modifying loadPacketsForLoopingSequence to accept a parameter, but I haven't gotten that far yet.
I like this solution because it stays in MIDI time and doesn't modify the MIDI file in unexpected, stateful ways. (New notes basically get streamed in when you get close enough to a loop marker.)

as3 array of objects - movement with constant speed

Ok, so I have some experience with as3 and some of the basics. But this problem has been stumping me for so long. I tried to do a workaround based on what I currently know about as3. But somehow either i get an error message or it just doesn't do anything at all. Here is the code that i'm trying to solve.
var zombieCount:Array = new Array();
var helltime:Timer = new Timer(1500);
helltime.addEventListener(TimerEvent.TIMER, spawnzombies)
helltime.start();
function spawnzombies(happened:TimerEvent){
var zombie1:Zombie = new Zombie();
zombieCount.push(zombie1);
stage.addChild(zombieCount[zombieCount.length - 1]);
zombie1.x = 135 + (330*Math.random())
zombie1.y = -29
stage.addEventListener(Event.ENTER_FRAME, move_zombie)
function move_zombie(happened:Event){
for(var i:int; i < zombieCount.length; i++){
zombieCount[i].y = zombieCount[i].y + 1;
if(zombieCount[i].hitTestObject(border)){
stage.removeChild(zombieCount[i]);
zombieCount.shift();
trace(zombieCount.length);
}
}
}
}
While this may not be inclusive of everything wrong, here are at least a few of the issues I see.
Inline function issue:
Inside your timer tick handler (spawnZombies), you create an inline function called move_zombie and then add an enter frame handler that calls that function.
The issue here, is that every tick of the timer, will then create a whole new copy of that function, and add ANOTHER enter frame handler. This will create huge problems after a few timer ticks.
Break that move_zombie function OUT OF the spawn function:
eg:
helltime.addEventListener(TimerEvent.TIMER, spawnzombies)
helltime.start();
stage.addEventListener(Event.ENTER_FRAME, move_zombie);
function move_zombie(......
function spawnzombies(.....
Iteration issue:
In your for loop:
for(var i:int; i < zombieCount.length; i++){
zombieCount[i].y = zombieCount[i].y + 1;
if(zombieCount[i].hitTestObject(border)){
stage.removeChild(zombieCount[i]);
zombieCount.shift();
trace(zombieCount.length);
}
}
You are not initializing your i value. While this will default it to 0, it's still a good idea for readability to initialize it.
So your iterating forward from 0 to the end of the array. However, if your hit test succeeds, you then use the shift method of the array. This removes the first item of the array (irrespective of what value i is at the time). This will remove the wrong item, plus mess up what zombieCount[i] refers to (because the amount of items has now changed after doing shift, so the next iteration zombieCount[i] will be a reference to same item as the previous iteration).
Instead of what you're currently doing, use the splice method to remove, and iterate backwards so your index doesn't get out of whack.
for(var i:int=zombieCount.length-1;i >=0;i--){
zombieCount[i].y += 1; //move it down 1 pixel
if(zombieCount[i].hitTestObject(border)){
stage.removeChild(zombieCount[i]);
zombieCount.splice(i,1); //remove the item at the current index (do this instead of shift)
trace(zombieCount.length);
}
}

Lua determining when out of range

I have a function called preprocess. It looks like this
function image_utils.preprocess(meanfile, oneD_image_table)
local img_mean = torch.load(meanfile).img_mean:transpose(3,1)
return function()
for t_class, img_path in pairs(oneD_image_table) do
local im3 = image.load(img_path)
local im4 = image.scale(im3,227,227,'bilinear')*25
return im4 - image.scale(img_mean, 227, 227, 'bilinear')
end
end
Here's how I call it:
im_f = image_util.preprocess(meanfile, path_list)
repeat
im=im_f()
batch[count]:copy(im)
count = count + 1
until count == batchSize
This works. However, I would like to be detect when im_f doesn't have any more iterations left and use that to determine when I should stop looping.In other words, something like this:
repeat
im = im_f()
count = count+1
batch[count] = im
until im == nil (or im is some sentinel value that tells me to stop)
However, I have not been able to make this work due to out of range error.
In short, I want to loop until im_f tells me to stop; rather than using a predetermined number to tell me when to stop.

Clearing my array leaves blank array positions

So I'm facing a problem with an AS3 class that's not operating the way I need it to. It's a simple problem, but a complex set of methods that cause it.
Firstly, the 'quiz' I'm building has 6 questions loaded as external SWFs inside of a Shell, run by a class. First we declared a var "a_quiz" to hold 6 values pushed from the external SWFs. These 6 values are reduced to a string and then checked against another array that contains the correct answers. The following loadQuiz function is designed to launch one of three random quizes and clear the a_quiz array so it can take new answers:
public function loadQuiz():void {
a_quiz.length=0;
trace("loadQuiz");
n_quizCorrect = n_quizScore = 0;
n_currentQuiz = Math.floor(Math.random() * (n_totalTopics - n_quizStart + 1) + n_quizStart);
loadTopic(n_currentQuiz);
}
Now I've tested the Shell and confirmed that the trace "loadQuiz" fires every time. And the first time you load the quiz, everything behaves as it should. The 6 questions trace correct or incorrect responses and push 6 binary values into the a_quiz array. The output looks like this:
loadQuiz
incorrect
correct
incorrect
incorrect
incorrect
incorrect
0,1,0,0,0,0
you failed
Then I jump back to the main menu and launch again. This deploys the loadQuiz function all over again. The first line of the function:
a_quiz.length=0;
should be emptying the a_quiz array to accept new answers to mark against. But when I complete the quiz I get this:
loadQuiz
correct
correct
correct
correct
correct
correct
,,,,,,1,1,1,1,1,1
you failed
For some reason beyond my understanding, the push values are stacking on top of empty positions, so when the strings compare...they won't match. What is going on here?
The push function:
function handleClick(evt:MouseEvent):void{
var tempCORRECT = a_answerSheet.toString();
var tempSELECTION = a_selected.toString();
//
if(tempSELECTION == tempCORRECT){
trace('correct');
parentObj1.a_quiz[ parentObj1.n_currentQuestion - 1 ] = 1;
}else{
trace('incorrect');
parentObj1.a_quiz[ parentObj1.n_currentQuestion - 1 ] = 0;
}
parentObj1.n_currentQuestion ++;
// GOTO NEXT SLIDE
parentObj1.LOADNEXT('up');
}
The problem originated in the loading of the Quiz itself.
as you can see on the handleClick function:
parentObj.n_currentQuestion++
was increasing an integer variable on the parentObj's timeline called n_currentQuestion. The problem then, originated in how the quiz was logging n_currentQuestion when the quiz loads with this function:
public function loadQuiz():void {
a_quiz= [];
trace("loadQuiz");
n_quizCorrect = n_quizScore = 0;
n_currentQuiz = Math.floor(Math.random() * (n_totalTopics - n_quizStart + 1) + n_quizStart);
loadTopic(n_currentQuiz);
}
So to correct the error, I needed to add a line to the loadQuiz, so that it would always load with n_currentQuestion set to 1.
public function loadQuiz():void {
a_quiz= [];
n_currentQuestion = 1;
trace("loadQuiz");
n_quizCorrect = n_quizScore = 0;
n_currentQuiz = Math.floor(Math.random() * (n_totalTopics - n_quizStart + 1) + n_quizStart);
loadTopic(n_currentQuiz);
}

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