Result from Native Call always Returns 1717986916

I have a very simple Java program that takes a double 16 array passes it to a Native C call. In the C function I take each element of the array and sum it up and return that sum. I followed some of the examples online and ran into this where each result returned was 1717986916 not matter what the was in the array. Any ideas what I am doing wrong? Here are my activity and c code.

public class NDKFooActivity extends Activity implements OnClickListener {
     // load the library - name matches jni/Android.mk
    static {
        System.loadLibrary("ndkfoo");
    }

    // declare the native code function - must match ndkfoo.c
    public static native int sumFIR(double[] arr);

    private TextView textResult;
    private Button buttonGo;
    private double[] dList = new double[16];
    private List<Double> list = new LinkedList<Double>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        textResult = (TextView) findViewById(R.id.textRes开发者_开发知识库ult);
        buttonGo = (Button) findViewById(R.id.buttonGo);
        buttonGo.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        String out = "";

        /////////////////////////////////////
        //load first 16 data sets

        list.add(2135.1); list.add(1130.1); list.add(2530.1); list.add(2430.1);
        list.add(2330.1); list.add(1940.1); list.add(1210.1); list.add(2100.1);
        list.add(2095.1); list.add(2105.1); list.add(2000.1); list.add(1876.1);
        list.add(1852.1); list.add(1776.1); list.add(1726.1); out += "" + add(1716.1);
        /////////////////////////////////////

        out += "\n" + add(2135.1);            out += "\n" + add(1130.1);
        out += "\n" + add(2530.1);            out += "\n" + add(2430.1);
        textResult.setText(out);
    }

    public double add(double object) {
        if (list.size() > 15 ) {
            list.remove(0);
        }
        list.add(object);
        for (int i=0; i< 16; i++) {
            dList[i] = list.get(i).doubleValue();
        }

        double dResult = sumFIR(dList);
        return dResult;
  }
} 

ndkfoo.c looks like this:

#include <stdio.h>
#include <stdlib.h>
#include <jni.h>

jdouble Java_com_nsf_ndkfoo_NDKFooActivity_sumFIR (JNIEnv* env, jobject obj, jdoubleArray arr) {
    jdouble result = 0;
    // initializations, declarations, etc
    jint i = 0;

    // get a pointer to the array
    jdouble *c_array = (*env)->GetDoubleArrayElements(env, arr, 0);
    jsize len = (*env)->GetArrayLength(env, arr);

    for (i=0; i<16; i++){
        result = result + c_array[i];
    }

    // release the memory so java can have it again
    (*env)->ReleaseDoubleArrayElements(env, arr, c_array, 0);

    // return something, or not.. it's up to you
    return result;
}

---

Okay found the answer turns out the Java native to the function was using int instead of double. Not sure why it almost always returned the same number.

// declare the native code function - must match ndkfoo.c
public static native int sumFIR(double[] arr);

Should be

public static native double sumFIR(double[] arr);