code: function geocentricFromWgs84(p, datum_type, datum_params) {
  
          if (datum_type === PJD_3PARAM) {
              //if( x[io] === HUGE_VAL )
              //    continue;
              return {
                  x: p.x - datum_params[0],
                  y: p.y - datum_params[1],
                  z: p.z - datum_params[2],
              };
  
          } else if (datum_type === PJD_7PARAM) {
              var Dx_BF = datum_params[0];
              var Dy_BF = datum_params[1];
              var Dz_BF = datum_params[2];
              var Rx_BF = datum_params[3];
              var Ry_BF = datum_params[4];
              var Rz_BF = datum_params[5];
              var M_BF = datum_params[6];
              var x_tmp = (p.x - Dx_BF) / M_BF;
              var y_tmp = (p.y - Dy_BF) / M_BF;
              var z_tmp = (p.z - Dz_BF) / M_BF;
              //if( x[io] === HUGE_VAL )
              //    continue;
  
              return {
                  x: x_tmp + Rz_BF * y_tmp - Ry_BF * z_tmp,
                  y: -Rz_BF * x_tmp + y_tmp + Rx_BF * z_tmp,
                  z: Ry_BF * x_tmp - Rx_BF * y_tmp + z_tmp
              };
          } //cs_geocentric_from_wgs84()
      }
docs: ************************************************************* pj_geocentic_from_wgs84() coordinate system definition, point to transform in geocentric coordinates (x,y,z)