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# Why is this code looping?

Asked by Amber on 10 Jul 2012
```%% Variables:
% aa,bb and x:counters
% bone: data of stress reading of a femer cantilevered with a different
% weight over a period of time
%
% averages1:averages of each basline
% averages2: x-coordinate where each jump occured
```
```clc;clear;close all
```
```time=-1:0.004:260.916;
% plot(time,bone)
% grid
% hold on
bone2 = smooth(bone,750);
figure
plot(time,bone2,'g')
hold on
grid
while length(averages1)<=17 && aa>=length(bone2)
for  x=1:1:70000; aa=x; bb=x+1;
difference=abs(bone2(aa)-bone2(bb));
if difference <= .009
flat(d)=[difference];
mean(difference)=averages1;
end
```
```          if difference >=.1
difference=abs(bone2(aa)-bone2(bb));
cc=length(bone2)-20000;```
```              averages2(cc)=[find(bone2,max),find(bone2,min)]
end
end```

I have written this code and it is supposed to find 17 averages and 17 jump points on the step function that gets plotted but it keeps looping after the 5th average. and I have no idea how to make the code find the jump points. Any help would be greatly appreciated.

Sebastian Holmqvist on 10 Jul 2012

Well, it's hard to see what you actually want to achieve with this code. But I notice that you never update averages1 inside of your loop. And since you don't have any break or return command this means that the while loop will just keep going.

Amber on 10 Jul 2012

it's suppose to compare the y-coordinates one by one and then when there's a big difference between them record the x-coordinate at that point. when there is a small difference between the (i.e. a straight line) it is supposed to give me the mean of that section of the plot

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Answer by John Petersen on 10 Jul 2012
Edited by John Petersen on 10 Jul 2012

You've got variables that aren't initialized, aa,d, and indices must be positive integers. 'difference' does not seem like a proper index. You clearly need to add an index, such as,

`    k = k+1;`

(also initialize it) and change the line

`    mean(difference)=averages1;`

to

```averages1(k) = mean(difference);
```

You might have other problems with your code, for example, aa never changes which is another test to stay in the loop. Can't see how you ever get in the loop without initializing that one.

Amber on 10 Jul 2012

That didn't change my output in anyway.

Amber on 10 Jul 2012

Thank you though! :)

John Petersen on 11 Jul 2012

that tells me that you're never satisfying the if(difference <=.009) test. Initialize averages1 and aa at least for good programming practice. Then single step through your program while observing how the variables are changing. This should give you some insight as to what's happening. Since I don't have your .mat files it's hard to debug it myself.