Re: [sdpd] STRUVIR: ACOS is greater than 1

[Armel Le Bail <armel...@fluo.univ-lemans.fr>]

>In STRUVIR:
>What does "The argument in ACOS is greater than 1" mean?
>How to fix the problem?

To fix that problem, you may :
   - change the VIEW direction, or, if inefficient
   - replace the VIEW command by the ROTA command and
     preferably do not use 0 or multiple of 90° in the ROTA
     command. Choosing ROTA 2. 2. 91. instead of ROTA 0. 0. 90.
     may fix that problem.
   - try WinStruplo by Louis Farrugia, which may have fixed the
      bug (I don't know because his source code is closed).
   - or fix it by yourself, looking inside the open source code

STRUVIR is the part I added inside STRUPLO for building
VRML output files. The above problem concerns the original
STRUPLO part, or at least is inside the 1991 STRUPLO
version I obtained from D.L. Ward in 1996. I was unable to fix that
problem because the STRUPLO Fortran code is, in my opinion,
quite hermetic. The program was built originally (1984-6) when
memory space was a problem, so that a few big arrays are reused
in various segmented forms with different meaning in many
subroutines. This organization has the consequence that the
code is quite complex to understand, and difficult to modify.
This was true also for SHELX-76.

A good new is that Antoine Le Lirzin, who introduced the
"bizarre" polyhedra recognition in STRUPLO (1989) has time
for looking again inside the code. He informed me very recently
that the STRUVIR code is not built from the most recent 
STRUPLO version (1993), highly debugged and including
the recognition of "open polyhedra". So that STRUPLO/STRUVIR
may well evolve again, thanks to him. Wait and see.

Best,

Armel Le Bail
http://www.cristal.org/course/