S-function error, How do I initialise the output correctly?

Hi Guys, I am currently using example code from Arduino to an S-Function where I am trying to output the acceleration values of X, Y and Z on a scope. I am getting an error for each axis when I try and upload the code to the arduino.

../Accelerometer_wrapper.cpp:73:9: error: assignment of read-only location '* y0'
   y0[0] = event.acceleration.x;
         ^
../Accelerometer_wrapper.cpp:74:9: error: assignment of read-only location '*(y0 + 4u)'
   y0[1] = event.acceleration.y;
         ^
../Accelerometer_wrapper.cpp:75:9: error: assignment of read-only location '*(y0 + 8u)'
   y0[2] = event.acceleration.z; 
         ^
*** [Accelerometer_wrapper.o] Error 1

The was I initialised the output is this way

if (xD[0]!=1) {
  #ifndef MATLAB_MEX_FILE
    /* Get a new sensor event */ 
  sensors_event_t event; 
  accel.getEvent(&event);

    /* Display the results (acceleration is measured in m/s^2) */

    y0[0] = event.acceleration.x;
    y0[1] = event.acceleration.y;
    y0[2] = event.acceleration.z;   

# endif
  xD[0]=1;
}

The way it is on the Arduino is

void loop(void) 
{
  /* Get a new sensor event */ 
  sensors_event_t event; 
  accel.getEvent(&event);

    /* Display the results (acceleration is measured in m/s^2) */
    Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print("  ");
    Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print("  ");
    Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.print("  ");Serial.println("m/s^2 ");
    delay(500);
  }

And since its an accelerometer, it doesn't require any inputs just one output with three rows. Any help would be appreciated. Thanks