The sodium ion may be abbreviated as Na+ or as simply Na. Sodium can occur as a salt in a crystalline solid. Sodium chloride (NaCl), sodium phosphate (Na2HPO4) and sodium bicarbonate (NaHCO3) are commonly occurring salts. These salts can be dissolved in water or in juices of various foods.
A Reference Point is something you use to determine the position of an object, but the reference point has to be something that doesn't move at all. For Example: A Tree. A Reference Point is something you use to determine the position of an object, but the reference point has to be something that doesn't move at all. For Example: A Tree.
A fixed point is a point that does not change upon application of a map, system of differential equations, etc. In particular, a fixed point of a function f(x) is a point x_0 such that f(x_0)=x_0. (1) The fixed point of a function f starting from an initial value x can be computed in the Wolfram Language using FixedPoint[f, x].