DEFINITION MODULE MathLib0;
(*
        Real Math Functions


From the book 'Programming in Modula-2' by Prof. N. Wirth.
*)


EXPORT QUALIFIED sqrt, exp, ln, sin, cos, arctan, real, entier;


PROCEDURE sqrt(x: REAL): REAL;
(* x must be positive *)

PROCEDURE exp(x: REAL): REAL;
(* returns e^x where e = 2.71828.. *)

PROCEDURE ln(x: REAL): REAL;
(* returns natural logarithm with base e = 2.71828.. of x *) 
(* x must be positive and not zero                        *)

PROCEDURE sin(x: REAL): REAL;
(* returns sin(x) where x is given in radians *)

PROCEDURE cos(x: REAL): REAL;
(* returns cos(x) where x is given in radians *)

PROCEDURE arctan(x: REAL): REAL;
(* returns arctan(x) in radians *)

PROCEDURE real(x: INTEGER): REAL;
(* type conversion from INTEGER to REAL *)

PROCEDURE entier(x: REAL): INTEGER;
(* returns the integral part of x.               *)
(* If this cannot be represented in an INTEGER,  *)
(* the result is undefined.                      *)

END MathLib0.