question: private float [ ] [ ] doPolarFillCorrection ( float [ ] xpoints , float [ ] ypoints , int y1 ) { float [ ] [ ] ret = new float [ 2 ] [ ] ; int len = xpoints . length ; float [ ] alt_xpts = new float [ len + 2 ] ; float [ ] alt_ypts = new float [ len + 2 ] ; System . arraycopy ( xpoints , 0 , alt_xpts , 0 , len ) ; System . arraycopy ( ypoints , 0 , alt_ypts , 0 , len ) ; alt_xpts [ len ] = alt_xpts [ len - 1 ] ; alt_xpts [ len + 1 ] = alt_xpts [ 0 ] ; alt_ypts [ len ] = y1 ; alt_ypts [ len + 1 ] = alt_ypts [ len ] ; ret [ 0 ] = alt_xpts ; ret [ 1 ] = alt_ypts ; return ret ; }
target:  Create alternate x,y coordinate arrays for rendering graphics the encompass a pole in the Cylindrical projection.