nl_tokens: Returns the position halfway between two positions . Chiefly used to test interpolate .
pl_tokens: function midpoint ( pos1 , pos2 ) { var Bx = Math . cos ( pos2 . φ) ath. c os( p os2. λ  - p s1.λ ) ; var By = Math . cos ( pos2 . φ) ath. s in( p os2. λ  - p s1.λ ) ; return { φ: tan2( s in( p os1. φ )  + s n(p o s2.φ ) , sqrt ( ( <mask> ( pos1 . φ) x) c os( p os1. φ )  + B )  + B  * B )) , λ: os1. λ  + a an2(B y ,  c s(p o s1.φ )  + x } ; }