Rounds a numeric value to the nearest power of two toward negative infinity.
input value
rounded value
var v = floor2( 3.141592653589793 ); // returns 2.0
var v = floor2( 13.0 ); // returns 8.0
var v = floor2( -0.314 ); // returns -0.5
Rounds a numeric value to the nearest power of two toward negative infinity.