APPENDIX A  Predeclared Procedures and Functions  Abs (x)  ArcTan (x)  Chr(i)  Dispose (q)  Dispose(q,kl, ... ,kn)  Eof (f)  Eoln (f)  a Boolean function that returns true 1  f  the textfile f, when in inspection mode,  is positioned at an end-of-line marker. e(  .. n (f)  is an error if f  is undefined or  if  eof (f)  is true. Otherwise eoln (f)  I  .:tums false. If  f  is omitted, program pa­ rameter Input  is assumed.  a Boolean function that returns t ru  ~  if the file variable f  is in generation  mode, or if f  is positioned past the last COl Iponent in its sequence and f  is in inspec­ tion mode. eof (f)  is anerrorif f  is un! cfined. Otherwise eof (f)  returns false.  If  f  is omitted, program parameter Inpl  t.  is assumed.  a dynamic-allocation procedure that aeallocates an identified record variable q  i  and destroys the identifying value q.  DisF  ose (q, kl, ... , kn)  is an error if q is  nil or undefined. The value q must have been created by the long form of New and  kl, ... , kn  must select the same variants selected when q  was created.  a dynamic-allocation procedure that d .:allocates an identified variable q  i  and de­ stroystheidentifyingvalueq. Dispose  (1)  isanerrorifq isnil orundefmed.  The value q  must have been created by II  K~  short form of New.  a transfer function that returns the chi' racter whose ordinal number is the integer  parameter i. Ch r ( i )  is an error if such a character value does not exist.  an arithmetic function that computes the real arctangent (principal value) in ra­ dians of a real or integer parameter x.  an arithmetic function that computes  I  ~Ie  real absolute value of a real parameter x  or the integer absolute value of an integel parameter x.  2114 