The size of the indicated variable

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Yigit
Yigit 2011-11-20
Hi,
When I run the following code ;
i=0;
t0 = clock;
while etime(clock, t0) < 10
disp(clock);
pwm(i)=0;
i = i +1;
tic
while toc<secs
end
pwm(i)=1;
i = i +1;
tic
while toc<secs
end
end
I get the following warning ;
The size of the indicated variable or array appears to be changing with each loop iteration. Commonly, this message appears because an array is growing by assignment or concatenation.
and application hangs even if it's a very simple algorithm.
Any ideas ?
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Yigit
Yigit 2011-11-20
forgot to mention ; variable "secs" is defined in the code, didn't post those parts not to cause pollution.

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回答（3 个）

Image Analyst
Image Analyst 2011-11-20
I don't know how big pwm might get. Maybe run it once to see. Let's say that it ends up being 100000 elements long. Then, before your while loop, you simply preallocate:
pwm = zeros(1, 100000);
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Image Analyst
Image Analyst 2011-11-21
I can't run your code because secs is undefined. What value are you using for it?
Yigit
Yigit 2011-11-22
secs change between 0.01 ~ 0.002

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Kostas
Kostas 2011-11-20
Is there any chance the variable secs to have such a little value that it is always litter than "toc"? In such a case your code goes into an infinite loop which cause it to hang.
Jan
Jan 2011-11-21
The code fails, because you try to access "pwm(i)" for i=0, but the index must be >= 1. When I start with "i=1;" the code runs successfully on my computer.
Where does the program fail on your computer? You can eitehr use the debugger or insert some disp command to check this.
I would avoid "tic; while toc<secs, end". A pause command would be smarter.
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Jan
Jan 2011-11-22
@Yigit: This is exactly the task of PAUSE.
Please provide the information I've asked for: *Where* does the program fail? It runs without problems on my machine...
Yigit
Yigit 2011-11-22
problem is when I plot(i,pwm(i)) plot only shows some of the signal, not the whole

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