Dipole model of the Earth's magnetic field (MLAT), or geomagnetic latitude, formula_10 is measured northwards from the equator (analogous to geographic latitude) and is related to formula_9 by formula_12. In this case, the radial and azimuthal components of the magnetic field (the latter still in the formula_9 direction, measured from the axis of the north pole) are given by formula_14 formula_15 formula_16 where formula_17 in this case has units of Earth radii (formula_18). Invariant latitude is a parameter that describes where a particular magnetic field line touches the surface of the Earth. It is given by formula_19 or formula_20 where formula_21 is the invariant latitude and formula_22
Dell Latitude the C6x0, D6x0, and E64x0 lines, but as of 2015 this line has been discontinued and replaced by both the 5 series and the 7 series. The 15" "Premium" line was the 8 series, until the E-series merged this line with the 6 series (Model numbers being along the lines of C8x0 or D8x0). The "budget" line was the 5 series, but as of 2015 the 5 series and 7 series Latitude laptops are the primary lines of Latitude laptops. The 3 series has replaced the 5 series as the budget line. Dell has also since dropped the E from