nl_tokens: Populates buffer buf from offset b with the center point of positions provided
pl_tokens: function centroid ( buf , b , ... p ) { var n = p . length / 2 ; var sum_x = 0 , sum_z = 0 , sum_y = 0 ; for ( let i = 0 ; i < n ; i += 1 ) { let i_φ  [ 2 ] , i_λ  [ 2 ] ; sum_x += <mask> ( i_φ) os( i _λ); sum_z += cos ( i_φ) in( i _λ); sum_y += sin ( i_φ) ; } var x = sum_x / n , z = sum_z / n , y = sum_y / n ; var r = sqrt ( x * x + z * z + y * y ) ; var φ  sin( y ) , λ  tan2( z , ) ; buf [ b + 0 ] = φ; buf [ b + 1 ] = λ; }