/*
      GW-Vectors.c
      Vector arithmetic for Gravity-Well
      Gary Teachout
      Copyright   July 1989
      lc -x GW-Vectors     To compile with Lattice 5.0
*/


 #include "GW-Include.h"


 void rotatedv( v , pv , s , c )
   struct dv *v , *pv  ;
   double *s , *c  ;
 {
   struct dv    t1 , t2  ;

   scaledv( v , c , &t1 )  ;
   scaledv( pv , s , &t2 )  ;
   adddv( &t1 , &t2 , v )  ;
 }

 
 void rotatedvpair10( x , y )    /* rotate vector pair 10 degrees */
   struct dv   *x , *y  ;
 {
   static double  srotate = 0.1736481776669303311 ,/* the sine and cosine */
                  crotate = 0.9848077530122081313 ,/* of 10 degrees       */
                  m1 = -1.0  ;
   struct dv   t1  ;

   scaledv( x , &m1 , &t1 )  ;
   rotatedv( x , y , &srotate , &crotate )  ;
   rotatedv( y , &t1 , &srotate , &crotate )  ;
 }


 void adddv( a , b , out )
   struct dv *a , *b , *out  ;
 {
   out->x = a->x + b->x  ;
   out->y = a->y + b->y  ;
   out->z = a->z + b->z  ;
 }


 void subdv( a , b , out )
   struct dv *a , *b , *out  ;
 {
   out->x = a->x - b->x  ;
   out->y = a->y - b->y  ;
   out->z = a->z - b->z  ;
 }


 void scaledv( a , b , out )
   struct dv *a , *out  ;
   double *b  ;
 {
   out->x = a->x * *b  ;
   out->y = a->y * *b  ;
   out->z = a->z * *b  ;
 }


 void dotdv( a , b , out )
   struct dv *a , *b  ;
   double *out  ;
 {
   *out =  a->x * b->x  +  a->y * b->y  +  a->z * b->z  ;
 }

/****    Gravity-Well does not use cross products
 void crossdv( a , b , out )     **     output must not go to input    **
   struct dv *a , *b , *out  ;
 {
   out->x =  a->y * b->z  -  a->z * b->y  ;
   out->y =  a->z * b->x  -  a->x * b->z  ;
   out->z =  a->x * b->y  -  a->y * b->x  ;
 }
****/

 void magdv( a , out )
   struct dv *a  ;
   double *out  ;
 {
   *out = sqrt( a->x * a->x  +  a->y * a->y  +  a->z * a->z )  ;
 }


 void basis( a , b , out )   /*     output must not go to input    */
   struct dv *a , *out  ;
   struct obv *b  ;
 {
   dotdv( a , &b->i , &out->x )  ;
   dotdv( a , &b->j , &out->y )  ;
   dotdv( a , &b->k , &out->z )  ;
 }