void xrot(double theta){
  theta*=(pi / 180);
  double ct=Math.cos(theta);
  double st=Math.sin(theta);
  float Nyx=(float)(yx * ct + zx * st);
  float Nyy=(float)(yy * ct + zy * st);
  float Nyz=(float)(yz * ct + zz * st);
  float Nyo=(float)(yo * ct + zo * st);
  float Nzx=(float)(zx * ct - yx * st);
  float Nzy=(float)(zy * ct - yy * st);
  float Nzz=(float)(zz * ct - yz * st);
  float Nzo=(float)(zo * ct - yo * st);
  yo=Nyo;
  yx=Nyx;
  yy=Nyy;
  yz=Nyz;
  zo=Nzo;
  zx=Nzx;
  zy=Nzy;
  zz=Nzz;
}

void xrot ( double theta ) { theta *= ( pi / 180 ) ; double ct = Math . cos ( theta ) ; double st = Math . sin ( theta ) ; float Nyx = ( float ) ( yx * ct + zx * st ) ; float Nyy = ( float ) ( yy * ct + zy * st ) ; float Nyz = ( float ) ( yz * ct + zz * st ) ; float Nyo = ( float ) ( yo * ct + zo * st ) ; float Nzx = ( float ) ( zx * ct - yx * st ) ; float Nzy = ( float ) ( zy * ct - yy * st ) ; float Nzz = ( float ) ( zz * ct - yz * st ) ; float Nzo = ( float ) ( zo * ct - yo * st ) ; yo = Nyo ; yx = Nyx ; yy = Nyy ; yz = Nyz ; zo = Nzo ; zx = Nzx ; zy = Nzy ; zz = Nzz ; }
rotate theta degrees about the x axis
