Convert retrieved values to double

We rely on MatlabControl to extract data from MATLAB and pass it to our
current JVM (if different). Unfortunately, the MatlabNumericArray class
can only wrap MATLAB double arrays. When unwrapped arrays are returned
directly their dimensionality is lost (a 1D array is returned).

So we must convert to double arrays using the MATLAB "double" function
to ensure data is wrappable by MatlabControl.

Author: hinerm

src/main/java/org/scijava/plugins/scripting/matlab/MATLABBindings.java

@@ -198,20 +198,37 @@ private Object retrieveValue(final Object key, final boolean remove) {
 
 		// Attempt to retrieve special MATLAB types
 		try {
+			// Only double arrays can be converted to MatlabNumericArrays.
+			// This is a highly aggressive conversion but currently no known
+			// alternative.
+			final String command = k + " = double(" + k + ");";
+			proxy.eval(command);
+
 			// try recovering key as a MatlabNumericArray
 			final MatlabTypeConverter converter = new MatlabTypeConverter(proxy);
 			v = converter.getNumericArray(k);
 		}
 		catch (final MatlabInvocationException e) {
-			logService.warn(e);
+			logService.warn("Could not convert: " + k +
+				" to a MatlabNumericArray.\n\tDimensionality information may be lost.");
 		}
 
-		try {
-			v = proxy.getVariable(k);
-			if (remove) proxy.eval("clear " + k);
+		if (v == null) {
+			try {
+				v = proxy.getVariable(k);
+			}
+			catch (final MatlabInvocationException e) {
+				logService.warn(e);
+			}
 		}
-		catch (final MatlabInvocationException e) {
-			logService.warn(e);
+
+		if (remove) {
+			try {
+				proxy.eval("clear " + k);
+			}
+			catch (MatlabInvocationException e) {
+				logService.warn(e);
+			}
 		}
 
 		return v;