question: @ Override public double cos ( int step ) { step = Math . abs ( step ) % steps ; if ( step < costable . length ) { return costable [ step ] ; } if ( step > halfsteps ) { step = steps - step ; if ( step < costable . length ) { return costable [ step ] ; } } step = halfsteps - step ; return - costable [ step ] ; }
target:  Get Cosine by step value.