30 Coordinate Systems and Transformation azimuthal angle, is measured from the x-axis in the xy-plane; and z is the same as in the Cartesian system. The ranges of the variables are 0. In the Cartesian system the coordinates are perpendicular to one another with the same unit length on both axes. A Polar coordinate system is determined by a fixed point, a origin or pole, and a zero direction or axis. Each point is determined by an angle and a distance relative to the zero axis and the origin.
![Cartesian Cartesian](/uploads/1/2/5/5/125578898/370427951.jpg)
I am dealing with a time series in polar coordinates and I am applying the Kalman filter for predictions. The time series is related with the satellite orbite.However my prediction and estimation for the variance are expressed in polar coordinates r,theta.I know how to convert my prediction in cartesian coordinates with the function f(r,theta).