Error using eval in matlabcontrol

问题

I used MatlabConrol to connect Java and MATLAB. I want to send an image path to MATLAB to process it with matching functions and give me back a number of similar images and paths, to show in the Java GUI.

I always get the same error when passing an image path to MATLAB:

Error using eval
Undefined function 'getinput' for input arguments of type 'char'.

Here's my MATLAB function:

function matlab = getinput(input)
results = hgr(input);

And my Java code:

imag = ImageIO.read(fileChoose.getSelectedFile());
ImagePath = fileChoose.getSelectedFile().getAbsolutePath();

public void SendingMatlabControl() throws MatlabConnectionException,
  MatlabInvocationException {
  // create proxy
  MatlabProxy proxy;
  // Create a proxy, which we will use to control MATLAB
  MatlabProxyFactory factory = new MatlabProxyFactory();
  proxy = factory.getProxy();
  // Display 'hello world' like before, but this time using feval
    try {
      // call builtin function
      proxy.eval("getinput('imagepath')");
      // call user-defined function (must be on the path)
      proxy.eval("addpath('E:\\vm')");
      proxy.feval("matlab");
      proxy.eval("rmpath('E:\\vm)");
    } catch (MatlabInvocationException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    // Disconnect the proxy from MatLab
    proxy.disconnect();
  }

回答1:

Let me give an example of calling a function, passing it input, and retrieving the output. There are two ways, either:

use eval and assign the result of the function inside the MATLAB workspace, then retrieve those variables using getVariable, or
use returningFeval to evaluate the function with its inputs, and directly retrieve the output.

Suppose we had a MATLAB function myfunc.m that takes a string as input, and returns a cell array containing a string, a number, and a vector:

function out = myfunc(str)
    out = cell(3,1);
    out{1} = sprintf('Welcome to %s!', str);
    out{2} = 99;
    out{3} = rand(10,1);
end

Here is the Java code:

import matlabcontrol.*;

public class TestMyFunc
{
    public static void main(String[] args)
        throws MatlabConnectionException, MatlabInvocationException
    {
        // create proxy
         MatlabProxyFactoryOptions options =
            new MatlabProxyFactoryOptions.Builder()
                .setUsePreviouslyControlledSession(true).build();
        MatlabProxyFactory factory = new MatlabProxyFactory(options);
        MatlabProxy proxy = factory.getProxy();

        // call function and get output cell array
        String in = "Stack Overflow";
        Object[] out = proxy.returningFeval("myfunc", 1, in);

        // extract stuff from cell array
        out = (Object[]) out[0];
        String str = (String) out[0];
        double x = ((double[]) out[1])[0];
        double[] arr = (double[]) out[2];

        // show result
        System.out.println("str =\n " + str);
        System.out.println("x = \n " + x);
        System.out.println("arr =");
        for(int i=0; i < arr.length; i++) {
            System.out.println(" " + arr[i]);
        }

        // shutdown MATLAB
        //proxy.feval("quit");

        // close connection
        proxy.disconnect();
    }
}

I get the output:

str =
 Welcome to Stack Overflow!
x =
 99.0
arr =
 0.5974901918725793
 0.3353113307052461
 0.29922502333310663
 0.45259254156932405
 0.42264565322046244
 0.35960631797223563
 0.5583191998692971
 0.7425453657019391
 0.42433478362569066
 0.42935578857620504

来源：https://stackoverflow.com/questions/11279998/error-using-eval-in-matlabcontrol

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java

matlab

matlab-deployment