Re: [ESPResSo-users] Question about the two compilation methods given in the manual

[Olaf Lenz]

Hi Kai Yang!

Thanks for the very cleanly written problem report! It's a pleasure to
reply to such a report - it contains all required information, and there
are no demands. I hope that the speed and length of the reply honor this.

On 07/05/2012 10:29 AM, Kai Yang wrote:
> > code_info
> ESPResSo-3.1.0 { Compilation status { FFTW } { CONSTRAINTS } {
> COMFIXED } { NPT } { COMFORCE } { PARTIAL_PERIODIC } { LENNARD_JONES
>  } { EXTERNAL_FORCES } { TABULATED } { BUCKINGHAM } { SOFT_SPHERE } {
>  LJCOS } { LENNARD_JONES_GENERIC } { MASS } { BOND_ANGLE_COSINE } {
> ELECTROSTATICS } { LJCOS2 } { MPI_CORE } { MORSE } { FORCE_CORE } {
> EXCLUSIONS } }

This is the default set of features and is what is supposed to be the
outcome in both cases.

> > code_info
> ESPResSo-3.1.0 { Compilation status { FFTW } { CONSTRAINTS } {
> ROTATIONAL_INERTIA } { BOND_ENDANGLEDIST_HARMONIC } { GAY_BERNE } {
> BOND_ENDANGLEDIST } { COMFIXED } { INTER_RF } { NPT } { COMFORCE } {
>  LB_BOUNDARIES } { HERTZIAN } { BOND_ANGLEDIST_HARMONIC } {
> PARTIAL_PERIODIC } { LENNARD_JONES } { LJ_ANGLE } { OVERLAPPED } {
> MOLFORCES } { BMHTF_NACL } { MODES } { EXTERNAL_FORCES } { TABULATED
>  } { BUCKINGHAM } { LANGEVIN_PER_PARTICLE } { SOFT_SPHERE } { LJCOS }
>  { LENNARD_JONES_GENERIC } { MASS } { SMOOTH_STEP } {
> BOND_ANGLE_COSINE } { VIRTUAL_SITES_RELATIVE } { ELECTROSTATICS } {
> LJCOS2 } { BOND_ANGLEDIST } { LB } { BOND_VIRTUAL } { NEMD } {
> LB_ELECTROHYDRODYNAMICS } { MORSE } { DIPOLES } { ROTATION } {
> COLLISION_DETECTION } { EXCLUSIONS } }

This is not what should happen, and I'm very surprised, as it contains a
number of very uncommon features.

Usually, this should only happen if out of some reason the build system
found a wrong myconfig.h.

The build system looks for the myconfig.h-files in the following
locations, in that order:

  $builddir/myconfig.h
  $srcdir/myconfig.h
  $srcdir/src/myconfig-default.h

Does any of these files exist and contain the features that you saw in
the build?

If not, could you please check the file $builddir/src/myconfig-final.h?
That is the config file that is actually used for the build, and it
should be a copy of the file above.

If that doesn't help, please send me the file "config.log" that you
should find in the build directory.

> The information given by two methods is different! Why does this
> difference produce? Will the compile methods influence the simulation
> results?

If you do not specify your own myconfig.h, both ways of compiling
ESPResSo should in theory generate the same binary with the same default
features (that you can see in $srcdir/src/myconfig-default.h). In your
case, there seems to be some kind of problem.

Simulations should usually not produce different results when different
features are turned on. In the worst case, the simulation does not run
at all, or it runs slower.

> Which compile methods should I choose?

I always suggest people to use out-of-source builds, as this allows you
to compile various binaries with different features and compile flags
from the same sources. However, if you just plan a single build as you
are going to use a single set of features anyway, an in-source build
should suffice.

Olaf

--
Dr. rer. nat. Olaf Lenz
Institut für Computerphysik, Pfaffenwaldring 27, D-70569 Stuttgart
Phone: +49-711-685-63607

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