math - TypeError: object array may be self-referencing python

Question

So, I ran into this error:

temp7: 
1.68219771725e-06
temp6: 
[[array([-60800056.33037408], dtype=object)]]
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rospy/timer.py", line 223, in run
    self._callback(TimerEvent(last_expected, last_real, current_expected, current_real, last_duration))
  File "/home/husky/catkin_ws/src/huskybot_ekf_v2/src/meas_update.py", line 194, in meas_update_step
    thisJ = temp7 * math.exp(temp6)

It seems like on the very last line thisJ =temp7* math.exp(temp6), that I can't take the exponent of temp6. Does anyone know the cause?

for i in range(0,len(line_features)-1):
    for k in range(0, len(m)):
        mkx = m[k][0]
        mky = m[k][1]
        posex = predicted_pose.x
        posey = predicted_pose.y
        poseth = predicted_pose.theta

        distx = math.pow((mkx - posex), 2);
        disty = math.pow((mky - posey), 2);

        q = distx + disty
        angle = math.atan2(mky-posey, mkx-posex) - poseth

        expected_meas = numpy.array([[math.sqrt(q)],
                                    [angle],
                                    [0]
                                    ])

        H = numpy.array([[-(mkx-posex)/math.sqrt(q), -(mky-posey)/math.sqrt(q) , 0],
                        [(mky-posey)/q, -(mkx-posex)/q, -1],
                        [0 , 0, 0]])
        Qt = 0.5
        innovation_cov = H*predicted_cov*numpy.transpose(H)+Qt
        innovation = ave_meas_dist - expected_meas

        dd = [[2]]
        #dd = array[0]

        #print 0.5*numpy.array(dd)
        temp5 = -1/2 * numpy.dot(numpy.transpose(innovation), numpy.linalg.inv(innovation_cov))
        temp6 = numpy.dot(temp5, innovation)
        print math.sqrt(numpy.linalg.det(2*math.pi*innovation_cov)) * numpy.array(dd)
        temp7 = math.sqrt(numpy.linalg.det(2*math.pi*innovation_cov))
        thisJ =temp7* math.exp(temp6)

Answer 1

I tried to reproduce the error. The error I got is:

TypeError: must be real number, not list

If the error is same then it was solved by doing this:

thisJ = temp7 * math.exp(temp6[0][0])

Because temp6 type is list containing list containing array object. Please do correct me if I am wrong.