[ESPResSo] BOND_ANGLE_HARMONIC

[Mehmet Sayar]

Hi all,

In the bond_angle_harmonic routine shouldn't there be a check for
cosine > 1.0. In other words, I think the code should be corrected as:

#ifdef BOND_ANGLE_HARMONIC
 {
   double phi,sinphi;
   if ( cosine >  TINY_COS_VALUE ) cosine = TINY_COS_VALUE;
   if ( cosine < -TINY_COS_VALUE)  cosine = -TINY_COS_VALUE;
   phi =  acos(-cosine);
   sinphi = sin(phi);
   if ( sinphi < TINY_SIN_VALUE ) sinphi = TINY_SIN_VALUE;
   fac *= (phi - iaparams->p.angle.phi0)/sinphi;
 }
#endif

If everybody agrees, I will add this to the cvs.

P.S. I originally send this message to address@hidden But since 
that email did not show up in the email-thread, I am re-sending the message.
Is address@hidden still in use?

And I already got an answer from Hanjo to the email sent to address@hidden, 
which was:

> So far we have the checks only for functions with a singularity when
> cosine is aproaching 1 (and sinphi is aproaching 0). Can the scalar
> product yield values >1 ( <-1)? (which would yield an error in the acos
> function). If yes then add
>      if ( cosine >  1 ) cosine = 1;
>      if ( cosine < -1)  cosine = -1;
> To the corresponding force and energy routines.
>
> Greetings Hanjo

Does everyone agree? Any objections?

Greetings from Istanbul,

Mehmet
--
________________________________________________________
Mehmet Sayar - Assist. Prof.  Koc University
Email:address@hidden        Dept. Mechanical Eng.
Phone:+90-212-338-1840        Rumelifeneri Yolu, Sariyer
Fax:  +90-212-338-1548        34450 Istanbul, Turkey