Math formulae

The formulae to be numbered are those referred to in the paper, as well as the final formulae. The formula number should be written on the right-hand side of the formula in round brackets.

All notations should be written clearly. Special care must be taken to write small and capital letters as precisely as possible (this applies mainly to the letters c and C, s and S, and others whose shapes of the lowercase and uppercase letters differ slightly).

Vectors should be denoted by boldfaced type.

Trigonometric functions are denoted by sin, cos, tan and cot; inverse trigonometric functions – by arcsin, arccos, arctan and arccot; hyperbolic functions are denoted by sinh, cosh, tanh and coth. All functions must not be written in italics.