/* qtransform.cc */#include <math.h>#ifdef sgi    #include "qtransform.h"    #include <stdio.h>    #include <string.h>#else    extern "C"    {        #include "qtransform.h"        #include <stdio.h>        #include <string.h>    }#endifvoid qtransform( const Coord T,                 const Quat  q,                 float tcoord[MAX_ATOMS][SPACE],                 const int   natom)/******************************************************************************//*      Name: qtransform                                                      *//*  Function: Accelerated quaternion transformation                           *//*            Performs both a rigid-body translation and rotation.            *//*            Assumes quaternion vector q.nx,q.ny,q.nz is normalized outside  *//*            this routine.                                                   *//* Copyright: (C) 1995, TSRI                                                  *//*----------------------------------------------------------------------------*//*   Authors: Garrett M. Morris, The Scripps Research Institute               *//*            David Goodsell, UCLA                                            *//*      Date: 11/23/94                                                        *//*----------------------------------------------------------------------------*//*    Inputs: q, tcoord, natom                                                *//*            q[] contains (xt,yt,zt,x,y,z,w(radians))                        *//*   Returns: tcoord                                                          *//*   Globals: QUAT, MAX_ATOMS                                                 *//*----------------------------------------------------------------------------*//* Modification Record                                                        *//* Date     Inits   Comments                                                  *//* 05/15/92 GMM     Translated into C.                                        *//* 11/23/92 GMM     Introduced (15+,9*) version, replacing (12+,36*) version. *//******************************************************************************/{    register int a;    Coord  tmp;    double w, x, y, z;    double tx, ty, tz;    double omtxx;    double twx, txy, txz;    double twy, tyy, tyz;    double twz, tzz;    double r11, r12, r13, r21, r22, r23, r31, r32, r33;    w = q.w;    x = q.x;    y = q.y;    z = q.z;/*  12 adds, 36 multiplies...     *//*    r11 = 1. - 2.*y*y - 2.*z*z; *//*    r12 =      2.*x*y + 2.*w*z; *//*    r13 =      2.*x*z - 2.*w*y; *//*    r21 =      2.*x*y - 2.*w*z; *//*    r22 = 1. - 2.*x*x - 2.*z*z; *//*    r23 =      2.*y*z + 2.*w*x; *//*    r31 =      2.*x*z + 2.*w*y; *//*    r32 =      2.*y*z - 2.*w*x; *//*    r33 = 1. - 2.*x*x - 2.*y*y; *//*  15 adds, 9 multiplies...      */    tx  = x+x;    ty  = y+y;    tz  = z+z;    twx = w*tx;    omtxx = 1. - x*tx;    txy = y*tx;    txz = z*tx;    twy = w*ty;    tyy = y*ty;    tyz = z*ty;    twz = w*tz;    tzz = z*tz;    r11 = 1. - tyy - tzz;    r12 =      txy + twz;    r13 =      txz - twy;    r21 =      txy - twz;    r22 = omtxx    - tzz;    r23 =      tyz + twx;    r31 =      txz + twy;    r32 =      tyz - twx;    r33 = omtxx    - tyy;    for (a = 0;  a < natom;  a++) {        tmp.x = tcoord[a][X]*r11 + tcoord[a][Y]*r21 + tcoord[a][Z]*r31 + T.x;        tmp.y = tcoord[a][X]*r12 + tcoord[a][Y]*r22 + tcoord[a][Z]*r32 + T.y;        tmp.z = tcoord[a][X]*r13 + tcoord[a][Y]*r23 + tcoord[a][Z]*r33 + T.z;        tcoord[a][X] = tmp.x;        tcoord[a][Y] = tmp.y;        tcoord[a][Z] = tmp.z;    }}/* EOF */