Comments on: High Performance File I/O http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/ Loren Shure works on design of the MATLAB language at The MathWorks. She writes here about once a week on MATLAB programming and related topics. Mon, 06 Oct 2008 13:37:40 +0000 http://wordpress.org/?v=2.3.1 By: Eric http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-219 Eric Tue, 30 May 2006 10:44:25 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-219 Wow! That was a good one. I use a lot of fprintf in link level simulations of communication systems. The data is printed to files frame-by-frame, and the files are used to test Verilog implementation of the actual modem hardware. I've just tried your tip, and savings in simulation time are tremendous. Thank you! Eric Wow! That was a good one.

I use a lot of fprintf in link level simulations of communication systems. The data is printed to files frame-by-frame, and the files are used to test Verilog implementation of the actual modem hardware.

I’ve just tried your tip, and savings in simulation time are tremendous.

Thank you!

Eric

]]> By: Loren http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-151 Loren Wed, 26 Apr 2006 14:21:28 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-151 Pat- The only way to guarantee the buffer is flushed is to use <kbd>fclose</kbd> if you open with <kbd>A</kbd> or <kbd>A</kbd>. Using <kbd>a</kbd> or <kbd>w</kbd> flushes the buffer after each write. --Loren Pat-

The only way to guarantee the buffer is flushed is to use fclose if you open with A or A. Using a or w flushes the buffer after each write.

–Loren

]]> By: Loren http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-150 Loren Mon, 24 Apr 2006 11:33:45 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-150 I would recommend in the future sending information like this to our Technical Support group. They pass information like this along to the development team who then prioritize their work with user requests in mind. The link is: <p> http://www.mathworks.com/support/contact_us/ts/ebd/enhance_bug_doc_1.html </p> I would recommend in the future sending information like this to our Technical Support group. They pass information like this along to the development team who then prioritize their work with user requests in mind. The link is:

http://www.mathworks.com/support/contact_us/ts/ebd/enhance_bug_doc_1.html

]]> By: gianni http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-149 gianni Mon, 24 Apr 2006 07:23:26 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-149 Loren, I am writting in connection to a recent answer given by you to on the newsgroup and concerning out of memory problems ... Also with the most recent version of matlab (2006a) there are cases of routines that do not support single precision In my view this is a major problem for many users of matlab, and huge memory boards do not help as much as a matlab tuning to make single precison always possible I have a direct experience with stream3 that cannot be forced to use single precison and uses 3 huge gradient arrays in double thank you , Gianni %%%%% Chris >> > MATLAB supports arithmetic and lots of other math on singles for > MATLAB > 7. Perhaps upgrading would be beneficial for you. Loren,
I am writting in connection to a recent answer given by you to on the newsgroup and concerning out of memory problems …

Also with the most recent version of matlab (2006a) there are cases of routines that do not support single precision

In my view this is a major problem for many users of matlab,
and huge memory boards do not help as much as a matlab tuning to make single precison always possible

I have a direct experience with stream3 that cannot be forced to use single precison and uses 3 huge gradient arrays in double

thank you , Gianni
%%%%%
Chris
>>
> MATLAB supports arithmetic and lots of other math on singles for
> MATLAB
> 7. Perhaps upgrading would be beneficial for you.

]]> By: Pat Cantey http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-147 Pat Cantey Fri, 21 Apr 2006 22:38:06 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-147 When using this technique, is the only way to flush the buffer to call fclose? Or is there some other function call that will flush? Or does it automatically flush when the buffer reaches its limit? If so, what is the limit (in bytes)? When using this technique, is the only way to flush the buffer to call fclose?

Or is there some other function call that will flush?

Or does it automatically flush when the buffer reaches its limit? If so, what is the limit (in bytes)?

]]> By: John O'Leary http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-146 John O'Leary Wed, 19 Apr 2006 20:17:34 +0000 http://blogs.mathworks.com/loren/2006/04/19/high-performance-file-io/#comment-146 I haven't used it in awhile, but last time I did movie2avi seemed to run much slower than it should. I looked through the code and it seemed that the avi file created by this function was being opened and closed for every frame. After reading this post, I went back and looked at addframe.m again and I see this line (308): fid = fopen(filename,'a','l'); Could it be that simply changing the 'a' to 'A' here would speed up the writing of a movie to an avi file? I haven’t used it in awhile, but last time I did movie2avi seemed to run much slower than it should. I looked through the code and it seemed that the avi file created by this function was being opened and closed for every frame. After reading this post, I went back and looked at addframe.m again and I see this line (308):

fid = fopen(filename,’a',’l');

Could it be that simply changing the ‘a’ to ‘A’ here would speed up the writing of a movie to an avi file?

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