CODEWITHSUNDEEP
performancefilematlabsave
Karl
Karl

Reputation: 5733

The quickest way possible to save Matlab matrices

I am using Matlab to invoke some external call in C++ and then receive a huge calculated matrix back. The matrix is very huge, and I do not have access to this C++ program's source code. (if I have, I will make it save from C++ right away)

Right now, on my system, this C++ program only uses 1 second to calculate the given data and send back to Matlab, and Matlab's dlmwrite takes 200-300 seconds to save this single huge array on disk. I have some more thousands to compute, and I wanna cut the time down.

So what is the fastest way possible to save in Matlab?

Upvotes: 5

Views: 6331

Answers (2)

PaxRomana99
PaxRomana99

Reputation: 574

If you want a Matlab only solution, I would probably use fwrite for binary or fprintf for ASCII. However, I like to mix Matlab and Java when it comes to IO since this is usually faster. I would do something like

Java Code
package mypackage.release;

import java.io.DataOutputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException


public class MatrixWriter {
  public static void write(String fileName, double[] matrix) throws IOException {
    DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(fileName)));
    for (double d : matrix)
      dos.writeDouble(d);
    dos.close();
  }
}

Matlab Code
import mypackage.release.MatrixWriter;
M = get matrix from c++;
MatrixWriter.write('myfile.dat', M(:));

This is something off the top of my head, but I use variations of this all the time. Hope it helps.

Upvotes: 2

shoelzer
shoelzer

Reputation: 10708

The fastest way possible is probably Matlab's save command. Alternatively, you could fwrite the whole matrix to a binary file.

Using dlmwrite converts the values to text, which takes time and is more data to write to disk. Don't do that unless you really need to have the data in that format. Note that dlmwrite will be faster if called one time with a big matrix instead of in a loop that incrementally writes your file.

Upvotes: 5

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