<p>I remember seeing the code for a Highpass filter a few days back somewhere in the samples, however I can't find it anywhere now! Could someone remember me where the Highpass filter implementation code was?</p>

<p>Or better yet post the algorithm?</p>

<p>Thanks!</p>

From the idevkit.com forums:
```
```
#define kFilteringFactor 0.1
static UIAccelerationValue rollingX=0, rollingY=0, rollingZ=0;

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {

    // Calculate low pass values

    rollingX = (acceleration.x * kFilteringFactor) + (rollingX * (1.0 - kFilteringFactor));
    rollingY = (acceleration.y * kFilteringFactor) + (rollingY * (1.0 - kFilteringFactor));
    rollingZ = (acceleration.z * kFilteringFactor) + (rollingZ * (1.0 - kFilteringFactor));

    // Subtract the low-pass value from the current value to get a simplified high-pass filter

    float accelX = acceleration.x - rollingX;
    float accelY = acceleration.y - rollingY;
    float accelZ = acceleration.z - rollingZ;

    // Use the acceleration data.

}
```
```