Numeric function.

Some Numerical functions are introduced.

abs(n)  to return Absolute value.

sgn(n)  to return '+-'Sign mark.

sqr(n)  to return Square root.

int(n)  to return value of a decimal be discarded.

sin(n),cos(n),tan(n)  to return Trigonometric ratio.

 It is function which generate a random number 0~0.9999999.
 When generating from integer 0 to 9,
 Such description is used idiomatically.