AHRS with matlab and arduino

my ahrs sensor is sending data to matlab which processes it...the results of the processing needs to be sent to the arduino to run motors..
here is the matlab code...how do i interface my arduino deumilanove so that it can receive this data from the serial port send by matlab...is there any simple way of receiving this serial data on my arduino without going into the arduino libraries in matlab and using a usb domain only?

my ahrs sensor is sending data to matlab

How did you connect the sensor to matlab? Wasn't it a bit hard to solder the wires to the bits?

the results of the processing needs to be sent to the arduino to run motors

What results? Speed and direction?

here is the matlab code

Where?

how do i interface my arduino deumilanove so that it can receive this data from the serial port send by matlab

Start by losing the stupid buzzwords. Interface? What does that mean?

Having the Arduino read data from the serial port is trivial. Look at the Serial.available() and Serial.read() functions.

is there any simple way of receiving this serial data on my arduino

Yeah.

What's wrong with your shift key?

sorry for the vague question earlier...i am new to hardware...

I wanted to send some value from MATLAB to my arduino installed at say COM18. What are the steps i should follow? This should do my job.

Thanks.

Have you read this?
http://arduino.cc/playground/Interfacing/Matlab

Are there things that are missing/should be added?

my arduino is on com 18...i have uploaded the adiosrv.pde on the board..but when i try to connect using matlab i get this error...i tried plugging and unpluggin the arduino but yet the problem persisits... arduino.m is included in the folder...
where am i going wrong?

a=arduino('COM18')
Attempting connection ......
Warning: A timeout occurred before the Terminator was reached.
??? Error using ==> arduino>arduino.arduino at 100
Connection unsuccessful, please make sure that the Arduino is powered on, running
either adiosrv.pde or mororsrv.pde, and that the board is connected to the indicated
serial port. You might also try to unplug and re-plug the USB cable before
attempting a reconnection.

where am i going wrong?

There seems to be an issue with Windows and/or some applications handling of COM ports 10 or above.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1192119372
The Arduino side is supposed to have been fixed, but, perhaps Matlab hasn't. Try changing the serial port name to \.\COM18 and see if that helps.

Thanks a ton Paul. Hope this works. I had similar problem working on a Zigbee. Thanks again.
Cheers. Thanks for taking out time for such a trivial thing.

The problem still persists, I connected it to a COM port 6, and try to access by a=arduino('COM6') in Matlab but it still gives the same warning when i am using Windows(XP or 7). However, when i do the same in Linux (Ubuntu) it connects, what is the problem in Windows?
My port config is bps- 9600, data bits-8, parity- none, stop bits-1, flow- none. Can you please solve this problem? I have tried a lot of different things like installing uninstalling drivers, Matlab etc , but nothing changes in that Warning.