MPU6050 Complementary

[Willpower 0]

Hello everybody, I'm now working on Gy-521 MPU6050 and Stellaris Launchpad. I use the ported Jeff Rowberg's library from here (https://code.google.com/p/launchpad-stellaris-energia/wiki/Mpu6050Usage) and it work great to get the raw values from sensors. But when I apply complementary to compute the angles, it does not work whether I add the acc-angles calculation, it builds successfully but the serial monitor stop at "Initializing I2C devices...". I've attached my code below, anyone could help me out, thanks.
//Sorry for my bad english.

#include "Wire.h"
#include "I2Cdev.h"
#include "MPU6050.h"
#include "math.h"
MPU6050 accelgyro;

int16_t ax, ay, az;
int16_t gx, gy, gz;

bool blinkState = false;
float acc_x, acc_y, acc_z;
float gyro_x, gyro_y, gyro_z;
float base_ax, base_ay, base_az, base_gx, base_gy, base_gz;
float acc_angle_x, acc_angle_y, acc_angle_z;
float gyro_angle_x, gyro_angle_y, gyro_angle_z;
unsigned long last_read_time;
float last_x, last_y, last_z;
float dt, t_now;

void calib()
{
  int samples = 10;
  float acc_x_calib = 0;
  float acc_y_calib = 0;
  float acc_z_calib = 0;
  float gyro_x_calib = 0;
  float gyro_y_calib = 0;
  float gyro_z_calib = 0;
  int16_t Ax, Ay, Az, Gx, Gy, Gz;
  for(int i=0; i<samples;i++)
  {
    accelgyro.getMotion6(&Ax, &Ay, &Az, &Gx, &Gy, &Gz);
    acc_x_calib += float(Ax);
    acc_y_calib += float(Ay);
    acc_z_calib += float(Az);
    gyro_x_calib += float(Gx);
    gyro_y_calib += float(Gy);
    gyro_z_calib += float(Gz);
    delay(50);
  }
  base_ax = acc_x_calib/samples;
  base_ay = acc_y_calib/samples;
  base_az = acc_z_calib/samples;
  base_gx = gyro_x_calib/samples;
  base_gy = gyro_y_calib/samples;
  base_gz = gyro_z_calib/samples;
}

void set_last_read(unsigned long time, float x, float y, float z) 
{
  last_read_time = time;
  last_x = x;
  last_y = y;
  last_z = z; 
}

inline unsigned long get_last_time() { return last_read_time;}
inline float get_last_x() { return last_x; }
inline float get_last_y() { return last_y; }
inline float get_last_z() { return last_z; }

void setup() {
    // join I2C bus (I2Cdev library doesn't do this automatically)
    Wire.begin();

    // initialize serial communication
    // (38400 chosen because it works as well at 8MHz as it does at 16MHz, but
    // it's really up to you depending on your project)
    Serial.begin(9600);

    // initialize device
    Serial.println("Initializing I2C devices...");
    accelgyro.initialize();

    // verify connection
    Serial.println("Testing device connections...");
    Serial.println(accelgyro.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed");

    // configure Arduino LED for
    pinMode(GREEN_LED, OUTPUT);
    calib();
    set_last_read(millis(), 0, 0, 0);
}

void loop() 
{
    // read raw accel/gyro measurements from device
    accelgyro.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
    
    unsigned long t_now = millis();
    // these methods (and a few others) are also available
    //accelgyro.getAcceleration(&ax, &ay, &az);
    //accelgyro.getRotation(&gx, &gy, &gz);
    
    float acc_x = float(ax)/16384;
    float acc_y = float(ay)/16384;
    float acc_z = float(az)/16384;
        
    float gyro_x = (float(gx) - base_gx)/131;
    float gyro_y = (float(gy) - base_gy)/131;
    float gyro_z = (float(gz) - base_gz)/131;
    
    /* - not work
    float R2D = 180/M_PI;
    float acc_angle_y = atan2(acc_x,  sqrt(acc_y*acc_y + acc_z*acc_z))*R2D;
    float acc_angle_x = atan2(acc_y, sqrt(acc_x*acc_x + acc_z*acc_z))*R2D;
    float acc_angle_Z = atan2(sqrt(acc_x*acc_x + acc_y*acc_y), acc_z);
    */
    
    //filter gyro
    float dt = (t_now - get_last_time())/1000.0;
    float gyro_angle_x = gyro_x*dt + get_last_x();
    float gyro_angle_y = gyro_y*dt + get_last_y();
    float gyro_angle_z = gyro_z*dt + get_last_z(); 
    
    //Complementary
    float alpha = 0.96;
    float angle_x = alpha*gyro_angle_x + (1 - alpha)*acc_angle_x;
    float angle_y = alpha*gyro_angle_y + (1 - alpha)*acc_angle_y;
    float angle_z = gyro_angle_z;

    set_last_read(t_now, angle_x, angle_y, angle_z);
    
    //Serial.print
    Serial.print(acc_x, 2); Serial.print("\t");
    Serial.print(acc_y, 2); Serial.print("\t");
    Serial.print(acc_z, 2); Serial.print("\t");
    Serial.print(gyro_x, 2); Serial.print("\t");
    Serial.print(gyro_y, 2); Serial.print("\t");
    Serial.print(gyro_z, 2); Serial.println("\t");
    Serial.print(dt, 4); Serial.print("\t");
    Serial.print(angle_x, 3); Serial.print(",");
    Serial.print(angle_y, 3); Serial.print(",");
    Serial.print(angle_z, 3); Serial.println();
    
    // blink LED to indicate activity
    blinkState = !blinkState;
    digitalWrite(GREEN_LED, blinkState);
    delay(20);
}

[energia 485]

If I understand correctly then if you uncomment the following piece of code the Sketch runs fine?

//Complementary
    float alpha = 0.96;
    float angle_x = alpha*gyro_angle_x + (1 - alpha)*acc_angle_x;
    float angle_y = alpha*gyro_angle_y + (1 - alpha)*acc_angle_y;
    float angle_z = gyro_angle_z;