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Differences between FOROTS 5A(721) and FOROTS 6

See FOROTS.DOC for list of major differences


The numbers produced by FORLIB single  and  double  routines
are  more  accurate  (and  therefore  different  from  those
produced by version 5A) as a result of the  rewrite  of  the
library by IMSL.

The floating point input and output routines of FOROTS  have
been  made  more  accurate, so that the numbers they produce
(both internally and externally)  are  more  accurate  (and,
therefore different) than those produced by version 5A.

The maximum number of digits encoded by the  floating  point
output  routine  is increased in version 6 over that encoded
by version 5A.  Thus printing with format, say, E30.20  will
produce  different  results with version 6 than with version
5A:  for both real and double precision numbers  the  number
of non-zero digits has increased to 20.

FOROTS V6 does not ignore  nulls  encountered  in  a  DECODE
statement, whereas V5A did.  Null is an illegal character in
many of the conversion routines.

The action of the CLOSE statement has changed in version  6,
such that specification of any file parameters (e.g.  FILE=)
will cause a rename to be performed.  Version  5A  only  did
the rename if it detected an actual change.

With version 6, recordsize is enforced for input files.  The
actual record size used is the record size specified, plus 2
for the  carriage  return,  line  feed  sequence,  plus  the
padding  necessary  to  bring the record to a word boundary.
Thus the formula is ((RECSIZ+6)/5)*5.  Records read using  a
RECORDSIZE  specification  in  the  OPEN statement must have
precisely this calculated number of characters.   FOROTS  no
longer  stops  upon  reading  an  end-of-line character, nor
scans for them, in advancing to the next record.  However, a
premature   end-of-line   character  within  a  record  will
terminate the  characters  read  into  the  FOROTS  internal
record buffer.

FORTRAN-77 specifies default is BLANK=NULL  unless  no  OPEN
statement has been executed.  This conficts with 5A behavior
which is BLANK=ZERO.

A string of consecutive LFs is treated  as  one  LF  by  5A;
version 6 treats them as multiple records.

CALL ERRSET (n) now tells FOROTS to print out n warnings  of
each type.  ERRSET extensions...
CALL ERRSET(n,i) to set a limit for a specific error,
CALL ERRSET(n,i,x) to  call  subroutine  x  when  the  error

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occurs, after FOROTS error actions have occurred.

Integer division by  0  now  returns  the  largest  possible
integer  value having the sign of the numerator.  In version
5A, the value returned was the numerator.

Sequential files written with version  6  without  a  record
size specified are not padded with nulls to a word boundary,
whereas  version  5A  padded  to  a  word  boundary  to   be
compatible  with FORSE files.  This means that files written
sequentially without a record size  specified  in  the  OPEN
statement will, in general, not be readable as random-access
files.

The mixing of formatted and unformatted  data  in  the  same
file  is  not  supported  in  version  6,  whereas it was in
version 5A, albeit with many bugs.

With Version 5A, BLOCKSIZE for magtape  files  always  meant
words,  and  the  default  was 128 words for TOPS-10 and 512
words for TOPS-20.  With version 6, BLOCKSIZE is  in  bytes,
36-bit  bytes  for  binary  and  image mode files, and 7-bit
bytes for formatted (ASCII) files.  The default is still 128
words  for  TOPS-10  (640 bytes for formatted files), but is
1000 bytes  for  TOPS-20  (i.e.,  different  blocksizes  for
formatted and unformatted files).

The definitions of X and T formats have changed from  66  to
77 for output statements.  With -77, T and X do not actually
write blanks, they merely position the record pointer.  Only
the  actual  data  sets  the  record size, so that (A5,100X)
writes a 5-character record whereas (A5,100X,' ')  writes  a
106 character record.

With list-directed and namelist I/O, logical input  data  is
strictly  defined  as an optional period, followed by a T or
F, followed by any set of non-terminator characters.   There
will  no  longer  be  any diagnostic messages given for such
trashy input.

The default field width for F (with no field width supplied)
for  output  is  dependent  on  the  type of the variable in
version 6, and expands for extremely large  numbers,  rather
than  producing asterisks.  In version 5A, the default field
width was invariant for data type.

As an extension to the ANSI  standard,  list-directed  input
will  accept any data type for any variable type, and do the
kind of conversion done by the compiler.  This is also  true
for data preceded with a repetition count (e.g.  2*5.6 input
to a real variable and an integer variable will provide  5.6
to  the  real  variable and 5 to the integer variable).  The
exception is that if complex data is specified for a  double
precision  variable,  the DOUBLE PRECISION value of the real
part is transmitted to the double  precision  variable  (the

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compiler  truncates  it to a single precision value and sets
the 2nd word of the double precision variable to 0).

With list-directed and NAMELIST I/O, certain types  of  data
with  no  delimiters are interpreted differently by versions
5A and 6.  For instance, with  version  5A,  -1-1  are  read
differently  depending  on  whether the target variables are
integer or real:   it  reads  two  values  of  minus  1  for
integer, and -1E-1 for real.  Version 6 always reads -1-1 as
a single value (-1E-1) and converts it appropriately.

The ANSI standard specifies that random-access files have no
end.   Version  6  obeys  this  rule, which is a change from
version 5A.  Thus the END= branch will never be  taken,  and
should   not   be  used,  for  random-access  data  transfer
statements.

For formatted data and binary  unformatted  data,  the  ERR=
branch  will  be  taken for any unwritten record, whether in
the middle or at the end of the file.  Since there is no way
to know whether data has been written in an image mode file,
the ERR= branch cannot be used for this  purpose  for  image
mode files.

Since expressions will  be  allowed  in  I/O  statements  in
Fortran-77, and the expression evaluator decodes "#" as "not
equal", as of version 7 "#"  will  not  be  allowed  as  the
record  number  specifier  in  random-access  data  transfer
statements.  Version 6 gives a warning to that effect.

In I/O statements, after the format statement specifier  and
closing  paren  (if  any), DEC has allowed an optional comma
before the I/O list.  This comma is not allowed by the  ANSI
standard,  and  is  not  recommended  for  use.  There is no
guarantee that DEC compilers will support the  use  of  this
comma in future releases.

With version 6, if an error  is  encountered  in  reading  a
record,  the  file is positioned after the offending record,
so that a  backspace  will  position  the  file  before  the
offending record.  Version 5A positioned the file before the
offending record after an error.

In version 6, dollar format is defined  as  suppressing  the
carriage  return  and  one  line  feed  (if  any) that would
normally appear if the  next  data  transfer  were  a  WRITE
statement,  or  the  automatic <carriage return - line feed>
sequence that would normally be inserted by  FOROTS  if  the
next  data  transfer  were  a  READ  statement.  Field image
version 5A did not suppress the line feed for the succeeding
WRITE.