main/src/georegression/metric/UtilAngle.java
public static double toHalfCircle( double angle ) {
		if( angle < 0 )
			angle += Math.PI;
		if( angle > Math.PI/2.0 )
			angle -= Math.PI;
		return angle;
	}
public static double toHalfCircle( double angle ) {
		if( angle < 0 )
			angle += Math.PI;
		if( angle > Math.PI/2.0 )
			angle -= Math.PI;
		return angle;
	}
Converts an angle which is (-pi to pi) into a half circle angle (-pi/2 to pi/2).

@param angle Angle between -pi and pi.
@return -pi/2 to pi/2