Problem saving a file

I

I tried saving a file, got this error message

{Warning: Variable 'Res' cannot be saved to a MAT-file whose version is older than 7.3. To save this variable, use the -v7.3 switch. Skipping...}

( by using save function: save('a.mat','Res','-mat')

What does it mean?

Thanks,

Shani

[Roberto Herrera]

Hi Shani, I am dealing with the same problem saving a large 4-D matrix (>10GB) using -v7.3. It takes ages saving due to the compression in HDF. Reading is not a problem. You can map your file as a mat object (matObj), just read the "matfile" help, it works amazingly fast. Henry

Answer 1

[Walter Roberson]

It means that the variable is either more than 2 gigabytes, or contains a type of object that is not supported in older .mat files.

You should switch to

save('a.mat', 'Res', '-mat', '-v7.3');

[Shani Gal]

Thank you,

you are correct, the file is big, I was able to save, but it takes a long time to load it and to save it.

Do you know of a faster way to save and load large files ( it contains a matrix with 4 columns ) ?

[Walter Roberson]

In some cases, fwrite() and then fread() can be faster.

[Shani Gal]

Hi again,

My problem is that I have a lot of large files. Each file has a matrix with 4 columns and unknown number of rows. I need to search the 4th column of this matrix for a specific value and to retrieve the entire row the search finds.

I do the following:

a=load(a1.mat);

J=a(:,4)==Value

Out=a(J,:)

And it takes a lot of time to go over all the files. Have any idea how to speed it up?

Shani