Can I make a call to a third party Matlab function while using the Matlab Engine API along with Java?

I wish to use the MATLAB Engine API for running calculations along side a graphical user interface developed in Java on Eclipse IDE. Was wondering if it may be possible to make a call to third party functions written in MATLAB? Is there a way to zip a non-standard function along with the engine.jar found at the location: C:\Program Files\MATLAB\R2016b\extern\engines\java\jar ?

As a simple example, I would like to be able to run the function called 'apowb.m' which accepts two variables x1 and x2 and computes y=x1^x2.

 function [ y ] = apowb( x1, x2 )
 % This function evaluates y = x1 ^ x2
 y=x1^(x2);
 end

I make a reference to this function in my controller method in Java. Some snippets from that method are displayed below:

 import com.mathworks.engine.MatlabEngine;
 ...
 public class PersonOverviewController {

 private static Future<MatlabEngine> engFuture;
 private static MatlabEngine eng;
 ...
 @FXML
    private void calculate() throws Exception{
        engFuture = MatlabEngine.startMatlabAsync();
        eng = engFuture.get();
        double input1=5;
        double input2=6;
        Future<Double> future = eng.fevalAsync("apowb", input1, input2);
        System.out.println(future.get());
    }
 }

This throws a `null pointer exception' probably because the function "apowb" is not traced by the Java Compiler?

 Caused by: java.lang.NullPointerException
  at manan.gui.view.PersonOverviewController.calculate(PersonOverviewController.java:117)

Answer 1

[Bo Li]

Did you add "apowb" to the MATLAB path? You can do that using addpath either in MATLAB or through feval in Java. The M file needs to be searchable in order to be found by Java Engine.

http://www.mathworks.com/help/matlab/ref/addpath.html

[manan lalit]

I tried adding the function to the current matlabpath by using 'addpath' command in MATLAB, but I get the same error as before, upon running the java file in ECLIPSE:

Undefined function or variable 'apowb'.

Do you know if I can specify the location of apowb.m somewhere in Eclipse? Do you know if another option could be - compiling 'apowb.m' into a '.jar' format and then adding it to Eclipse as an external library?