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Re: name of the function that plot this noise

Sadik — Tue, 07 Feb 2012 08:34:10 -0500

Are you sure? It is not the 32nd row, it is the 32nd column.

Best.

Re: run() and parfor

Edric M Ellis — Tue, 07 Feb 2012 07:52:23 -0500

"Muni " <moonwatcher.mk@gmail.com> writes:

> I am curious what is the reason behind the following behavior. I made
> the following simple script that uses parfor:
> [...]
> Why is the output different when I run example.m directly on the
> command line and when I run it with the run() command?

Unfortunately, scripts containing PARFOR do not always work correctly
when running them using RUN. The workaround is to ensure the script is
on the path and invoke it directly.

Cheers,

Edric.

Re: Quickly list variables in a MAT-file

James Tursa — Tue, 07 Feb 2012 07:18:10 -0500

"Benjamin Kraus" <bkraus@bu.edu> wrote in message <jgprg6$mqc$1@newscl01ah.mathworks.com>...
>
> Thanks for your feedback. I'm not as familiar with MEX programming as I am with MATLAB in general (and my general C knowledge is very rusty), so I appreciate the input, especially regarding memory issues. Is mxFree(fname) sufficient to solve this "leak"? I assume this should be called just prior to any calls to mexErrMsg, and along with mxFree(dir) at the end of the function.

Yes. It will get garbage collected in any event so you don't risk a memory leak, but I usually like to clean things up myself unless it makes the code too messy. Once you call mexErrETC you exit the mex routine ... no code lines after that (within the same block) are executed.

> As you seem to be very knowledgeable of the issues, two more questions for you:
> (1) The documentation states: "In MEX-files... the MATLAB memory management facility maintains a list of all memory allocated by mxCalloc, mxMalloc, and mxRealloc."
> I've seen similar references to mxCalloc, mxMalloc, and mxRealloc in other places (including some of your posts I just found while trying to answer this question). What I've never seen explicitly stated is that memory allocated by other function, such as "mxArrayToString" or "matGetDir" are included under this umbrella.

mxArrayToString, matGetDir, etc all fall under this umbrella. Use mxFree to free such memory.

> If I'm understanding correctly, "mxArrayToString" and "matGetDir" both use mxMalloc internally to allocate the memory they use, which is why it is safe to use mxFree in those cases. Additionally, I'm not using mxDestroyArray because neither "fname" or "dir" are mxArray objects.

Correct. Use mxDestroyArray *only* on mxArray variables.

> (2) When I make the call:
> mexErrMsgIdAndTxt("matwho:fileerror","Error opening file: %s\n", fname);
>
> Is it possible to "properly" deallocate the memory used by fname? Am I right in assuming that putting "mxFree(fname)" as the next line would never actually be reached (just like the "return" that is already there, which I suppose I could probably remove)?

Yes, you are correct. Putting a mxFree(fname) after this line will not get executed, and the return never gets reached as well. In this case you either rely on the garbage collection to save you or you copy fname to some local variable of sufficient length to print out and then free fname prior to calling the mexErrETC routine. (Personally, I would just let the garbage collection handle it at this point and not worry about writing elaborate code to manually free it.)

--------------------------------------------

OK, here is the skinny on the MATLAB Memory Manager (MMM) in mex routines, at least as I understand it. The MMM keeps track of everything that gets allocated via API calls in a mex routine for the purposes of garbage collection. Whenever the mex routine exits (either normally or via an error) all of the memory on this garbage collection list is automatically deallocated. The MMM knows which memory is an mxArray and which memory is non-mxArray. But there are some subtleties involved.

When you allocate a new mxArray via the mxCreateETC functions, the mxArray is tagged as temporary and the address of the mxArray gets put on this internal garbage collection list. The mxArray will typically contain pointers to other memory, e.g. the pr and pi pointers that point to the real and imaginary data for numeric variables. Those pointers are *not* separately put on this garbage collection list. The MMM depends on the fact that they are connected to the mxArray to get them garbage collected. When an mxArray on the garbage collection list gets destroyed (either via garbage collection or via a mxDestroyArray call), the mxArray structure itself and all of the memory behind the data pointers of the mxArray also gets freed at the same time and the address of the mxArray is removed from the garbage collection list. I.e., this is a *deep* free and everything attached to this mxArray
will get freed. If the mxArray is a cell array, all individual cells will get destroyed. If the mxArray is a struct array, all individual fields will get destroyed. Etc.

When you use mxCreateETC to create an mxArray variable and then subsequently attach it to a cell or struct array via mxSetCell or mxSetField etc then the mxArray gets taken off of the garbage collection list and it gets marked as being a sub-element (to a cell or struct array). At this point, whether it gets garbage collected or not depends entirely on what happens to its parent. Technically, it has just become one of the data elements of the cell or struct array and would show up in the pr list for the parent.

When you call mexMakeArrayPersistent on an mxArray, the address of that mxArray gets removed from the garbage collection list. At that point you risk a memory leak unless you have specific code in place to destroy it (typically via a mexAtExit function). E.g., if you returned from the mex routine back to MATLAB without manually calling mxDestroyArray on it and without remembering its pointer inside the mex routine, then you would have a memory leak since it is still taking up memory and you have lost the only pointer to this memory. There would be no way to subsequently free the memory without restarting MATLAB.

When you allocate memory *other* than with the mxCreateETC API functions, such as mxMalloc, mxCalloc, mxArrayToString, etc, then the address of this memory gets put on the garbage collection list. If you call mexMakeMemoryPersistent on this address, then the address is removed from the garbage collection list. Again, you risk a memory leak at this point unless you have code in place that will free this memory via mxFree. Typically this would be accomplished via a mexAtExit function that you would write. Regardless of which non-mxArray API function allocated the memory, use mxFree to free it.

Rule of Thumb: Use mxDestroyArray to free mxArray variables, use mxFree to free all other API memory.

When you exit a mex routine normally, the plhs[*] array is examined and all mxArray variables on this list are removed from the garbage collection list before garbage collection takes place.

You can play games with this and get in trouble unless you understand what is going on. For example, suppose you use mxCreateDoubleMatrix to create an mxArray. Then you use mxGetPr to get the data pointer, and then use mxSetPr to set the pr pointer to NULL. I.e., you detach the data memory from the mxArray. This data memory is *not* on the garbage collection list since it was not originally put there by the mxCreateDoubleMatrix function. Remember, only the address of the mxArray itself gets put on the garbage collection list. The pr memory, once it gets detached from the mxArray, is essentially persistent memory at that point and you risk a memory leak unless you have code in place to explicitly free it.

Now suppose you create an empty mxArray via the mxCreateDoubleMatrix function (i.e., size 0 x 0). Then separately you allocate some data memory via mxMalloc. In this case the address of the mxArray variable *and* the address of the data memory are both separately put on the garbage collection list. Now suppose you attach the data memory to the mxArray via a mxSetPr call. The mxSetPr call does two things: It sets the pr pointer of the mxArray equal to this data memory address, *and* it removes the data memory address from the garbage collection list. At this point the disposition of the data memory will depend entirely on the parent and whether the parent gets garbage collected or not. Side Note: The mxSetPr call does *not* free up any pr data memory that is already attached to the mxArray, it simply overwrites the pr pointer value with a new value. So you again risk a memory leak unless
you manually free this preexisting pr data memory first.

James Tursa

Re: call masked java class

Alexander — Tue, 07 Feb 2012 07:15:10 -0500

"Yair Altman" wrote in message <jgq162$93b$1@newscl01ah.mathworks.com>...
> "Alexander " <student_vmk@mail.ru> wrote in message <jgor71$2an$1@newscl01ah.mathworks.com>...
> > Hi, I want to know is there any way to call masked java class?
> >
> > I want to use DefaultGroupTableModel from JIDE Grids. The problem is that matlab is shipped with Jide ver 2.7.7, which does not have all the features I need. I have the newer jide version, but there comes the problem:
> >
> > 1) If I simply use javaaddpath(), it adds the new jar to dynamic classpath, and it is masked by the jar from static classpath.
> >
> > 2) I can add new jar to static class path using ClassPathHacker:
> >
> > http://stackoverflow.com/questions/3580752/java-dynamically-loading-a-class/3581598#3581598ClassPathHacker.java
> >
> > but it is still masked by the matlab's old version (apperently it adds new file to the end of static class path).
> >
> > Btw, you can verify where java class is loaded from using nice script from:
> >
> > http://stackoverflow.com/questions/4376565/java-jpa-class-for-matlab
> >
> > 3) I can actually replace all jide jars in \MATLAB\R2010b\java\jarext\jide, and it works. But side effect is that Matlab is not completely compatible with new version (Help, Variable Editor and some other stuff doesn't work properly).
> >
> > So, is there any way to call the class from newer Jide version, without replacing old jars that are needed for correct work of Matlab?
> >
> > Thanks in advance,
> >
> > Alexander.
>
>
> You can selectively replace items on the static classpath by editing the %matlabroot%\toolbox\local\classpath.txt file. Or you can move your JARs to the top of the list in that same file.
>
> To fix the compatibility issue with Matlab's Help etc., try using a non-latest version of JIDE. A lot of changes happened between 2.7.7 (dated exactly 2 years ago) and the latest version (currently 3.3.4). The full list is given in http://www.jidesoft.com/history/ - try using JIDE versions at 3-6 month increments until you find one that works for both your needs and Matlab's.
>
> For anyone interested, using JIDE tables (grids) in Matlab is extensively discussed in Sections 4.1 and 5.7 of my Matlab-Java Programming book.
>
> Yair Altman
> http://UndocumentedMatlab.com
>

The idea with versions is good, but it doesn't help. The feature I need (->(Grids) Made GroupTableHeader and NestedTableHeader could work together with AutoFilterTableHeader.) is only available from 3.1.0, and Matlab has compatability problems at least from 2.11.4

Changing classpath.txt will have the same result as just replacing the Jars, i.e. I will still have problems with Matlab's Help and Variable Editor. I guess I'll just have to live with it is there's no other option...

load data into uitable's popup menu

jar head — Tue, 07 Feb 2012 07:08:10 -0500

I need to import data from uitable1 in figure1 and use it as input to a popup menu located inside uitable2 in figure2. I cant input the data by hand, the data from table1 (figure 1) is huge and evolves with time...

To be more precise, each cell of the "choice list" of a given column must present the data taken from uitable1 - figure1. I cant use data import as there are other non-related columns beside this popup menu column

Thanks for the support

Power electronics IEEE transaction projects

ASHOK KUMAR ARROJU — Tue, 07 Feb 2012 06:33:09 -0500

How to Choose a Project in Post Graduation and Under Graduation in Power Electronics or any Power Related Master courses .

Why we are doing Projects in Matlab/Simulink ?

If You Have any Doubts and You want any power electronics Project Guidance contact me.....

Re: JAVA BUILDER ERROR...????

THANH — Tue, 07 Feb 2012 05:54:10 -0500

Hello Ganesh,
Thanks for your answer. When I typed mbuild-setup on my matlab(r2011a), there was no java compiler-jdk available there (although i already installed jdk 1.7 on my computer).
So, how could i add java-jdk to matlab compiler?
Thanks.

if-else statements

Jasper Adamek — Tue, 07 Feb 2012 05:54:10 -0500

Write an if-else statement that checks whether the size of two arrays is equal or not. If the arrays are of different sizes, make their sizes equal by appending zeroes at the end of the smaller array.

HOW DO I DO THIS????

Load frequency Model with Matlab

Michael Bernard — Tue, 07 Feb 2012 04:58:10 -0500

Is there any load frequecy demo in Matlab. Or lets say, is there any model in matlab with DFIG wind farm for frequency control studies? I am currently researchig on frequency control of power system with DFIG. I need to see a Matlab demo to help me . I pray that someone will please reply urgently to this message here or sent email to mzbernard@yahoo.com.

Thanks

Michael

Image Extraction & Movement

Jayanth — Tue, 07 Feb 2012 04:58:10 -0500

Hey Guys,

I'm new to Matlab and I'm stuck with a problem.
I'm trying to extract a character from a text image and move it by a range of say, 10 pixels or so...

I've written just a simple code to extract each character and move it by just one pixel but i want to move one or more characters by a certain amount of pixels...

Thank You in advance.

Re: Symbolic solve and assign results to symbols

Ronald — Tue, 07 Feb 2012 04:51:10 -0500

The thing is my actual program will be solving for big systems of equations with many variables, and in a loop.

x=sym('x',[3,2]) % 6 variables
y=sym('y',[2,2]) % 4 variables

equations = [ ... , .... , ...]
restrictions = [ ... , ... , ... ] % total of 10 equations stored in 2 arrays

s=solve(equations, restrictions)

Instead of just returning a struct array, I want Matlab to assign the results (converted to double) directly to the respective symbols (x1_1, x1_2, ... , y2_2) after solving.

Re: fingerprint reconstruction

TideMan — Tue, 07 Feb 2012 04:48:08 -0500

On Feb 7, 4:37 pm, "raviprasadh ramalingam "
<raviprasadh....@gmail.com> wrote:
> Hi guys i am doing my final year project "finger print reconstruction from minutiae to phase". For the implementation of first module reconstruction of orientation field i need matlab codings. I had tried many functions but i cant get the output. So someone who have already done it please send it to my mail id
> raviprasadh....@gmail.com.

But if I give you the code I developed for my final year project, what
will that leave you to do?
And will you claim the credit for the code I have developed?

fingerprint reconstruction

raviprasadh ramalingam — Tue, 07 Feb 2012 03:37:10 -0500

Hi guys i am doing my final year project "finger print reconstruction from minutiae to phase". For the implementation of first module reconstruction of orientation field i need matlab codings. I had tried many functions but i cant get the output. So someone who have already done it please send it to my mail id
raviprasadh.svm@gmail.com.

projecting a circle onto the surface of a sphere

merew — Tue, 07 Feb 2012 02:41:10 -0500

can somebody show me how i can project a circle onto the surface of a unit sphere? say the radius of the circle is 0.25
Thanks in advance!

regular expression problem

Timothy Hilton — Tue, 07 Feb 2012 02:35:10 -0500

hi list,

I have ASCII data in the form
10/19/2009 17:30:00 -0.008397684 10.7973 <more tab-delimited numbers>

I want to pull out the time stamps. I thought a regular expression would be the ticket.

It seems to me that all six of these regular expressions (see
code snippet below) should match my string. Only 1, 2, and 6
produce a match, though.

Bug? Or am I missing something?

Thanks!
Tim

========================

date_re = '(\d\d){1,2}[\/\-]\d\d[/-]\d\d{1,2}';
% match hh:mm or hh:mm:ss
time_re = '\d\d:\d\d(:\d\d){0,1}';

str = [ 49, 48, 47, 49, 57, 47, 50, 48, 48, 57, 9, 49, 55, 58, 51, 48, 58, 48, 48, 9, 45, 48, 46, 48, 48, 56, 51, 57, 55, 54, 56, 52, 9, 49, 48, 46, 55, 57, 55, 51 ];

disp( char( str ) )

regexp( char( str ), date_re, 'match' ) % 1
regexp( char( str ), time_re, 'match' ) % 2
regexp( char( str ), [ date_re, '\s+', time_re ], 'match' ) % 3
regexp( char( str ), [ date_re, '(\s*)', time_re ], 'match' ) % 4
regexp( char( str ), [ date_re, '\t', time_re ], 'match' ) % 5
regexp( char( str ), [ date_re, '.*', time_re ], 'match' ) % 6

========================
my output using R2011b on a mac:
10/19/2009 17:30:00 -0.008397684 10.7973

ans =

    '10/19/200'

ans =

    '17:30:00'

ans =

     {}

ans =

     {}

ans =

     {}

ans =

    '10/19/2009 17:30:00'