A magnetic field sensor for determining a position of a magnet, the position identified by one or more position variables can include: one or more magnetic field sensing element operable to generate one or more magnetic field measurements of the magnet and an associated one or more measured magnetic field variable values; a first module for identifying calculated magnetic field variable values associated with a plurality of positions of the magnet; a second module operable to perform an optimization process to determine a value of a distance function, the distance function using the one or more measured magnetic field variable values and the calculated magnetic field variable values; and a third module operable to determine the position of the magnet by associating the value of the distance function with corresponding values of the one or more position variables. A complimentary method can be used in the magnetic field sensor.