``````/*
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
*
* CitcomS by Louis Moresi, Shijie Zhong, Lijie Han, Eh Tan,
* Clint Conrad, Michael Gurnis, and Eun-seo Choi.
* Copyright (C) 1994-2005, California Institute of Technology.
*
* This program is free software; you can redistribute it and/or modify
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*
*
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/

/* Common functions relating to the building and use of mesh locations ... */

#include <math.h>
#include "global_defs.h"

/* =================================================
this routine evenly divides the arc between points
1 and 2 in a great cicle. The word "evenly" means
anglewise evenly.
=================================================*/

void even_divide_arc12(elx,x1,y1,z1,x2,y2,z2,theta,fi)
double x1,y1,z1,x2,y2,z2,*theta,*fi;
int elx;
{
double dx,dy,dz,xx,yy,zz,myatan();
int j, nox;

nox = elx+1;

dx = (x2 - x1)/elx;
dy = (y2 - y1)/elx;
dz = (z2 - z1)/elx;
for (j=1;j<=nox;j++)   {
xx = x1 + dx*(j-1) + 5.0e-32;
yy = y1 + dy*(j-1);
zz = z1 + dz*(j-1);
theta[j] = acos(zz/sqrt(xx*xx+yy*yy+zz*zz));
fi[j]    = myatan(yy,xx);
}

return;
}

/* =================================================
rotate the mesh
=================================================*/
void rotate_mesh(E,m,icap)
struct All_variables *E;
int icap,m;
{

int i,lev;
double t[4],myatan();

for (lev=E->mesh.levmin;lev<=E->mesh.levmax;lev++)  {
for (i=1;i<=E->lmesh.NNO[lev];i++)  {
t[0] = E->X[lev][m][1][i]*E->sphere.dircos[1][1]+
E->X[lev][m][2][i]*E->sphere.dircos[1][2]+
E->X[lev][m][3][i]*E->sphere.dircos[1][3];
t[1] = E->X[lev][m][1][i]*E->sphere.dircos[2][1]+
E->X[lev][m][2][i]*E->sphere.dircos[2][2]+
E->X[lev][m][3][i]*E->sphere.dircos[2][3];
t[2] = E->X[lev][m][1][i]*E->sphere.dircos[3][1]+
E->X[lev][m][2][i]*E->sphere.dircos[3][2]+
E->X[lev][m][3][i]*E->sphere.dircos[3][3];

E->X[lev][m][1][i] = t[0];
E->X[lev][m][2][i] = t[1];
E->X[lev][m][3][i] = t[2];
E->SX[lev][m][1][i] = acos(t[2]/E->SX[lev][m][3][i]);
E->SX[lev][m][2][i] = myatan(t[1],t[0]);
}
}    /* lev */

return;
}
``````