11.5.2. Boolean functions. Let  i  be any integer expression, and let  f  denote any file variable. The result type of each Boolean function is  Boolean.  Pascal Report  193  sin (x)  yields the sine of x, where x  is in radians.  cos (x)  yields the cosine of x, where x  is in radians.  exp (x)  yields the value of the base of natural logarithms raised  to the power  x.  ln (x)  yields the natural logarithm of x. It is an error if x is less  than or equal to zero.  sqrt (x)  yields the square root of x. It is an error if x is negative.  arctan (x)  yields the principal value, in radians, ofthe arctangent  ofx.  odd (i)  is equivalent to the expression  i  mod  2  =  1.  eo f ( f)  is an error if f  is undefined; otherwise, eo f ( f)  yields  true if  f  is in generation mode or if  f  is positioned past  the last component in its sequence.  If  the parameter list  is omitted, eof  is applied to the program parameter  Input.  eoln (f)  is an error if f  is undefined or if eof (f)  is true. f  must  be  a  textfile.  Eoln  (f)  yields  true  if the  current  component of the sequence of  f  is  an end-of-line  marker.  If  the parameter list is omitted, eoln is applied  to the program parameter  Input.  11.5.3. Transfer functions. Let  r  denote a real expression. The result  type of these functions is Integer.  t rune (r) yields a value such that if r  >=  0  then 0  <=  r  - trune(r)  <  1, and if r  <  0  then -1  <  r  - t rune (r)  <=  o. It is an error if no such value exists.  round (r) yields a value such that if r  >=  0  then round (r)  =  trune(r  +  0.5), and if r  <  0  then round(r)  =  t rune (r - 0.5). It is an error if no such value exists.  11.5.4 Ordinal functions. Let  i  be an integer expression, and let x be  any ordinal expression. 