function trunc( x ) {
	if ( x < 0.0 ) {
		return ceil( x );
	}
	return floor( x );
}
Rounds a double-precision floating-point number toward zero.

@param {number} x - input value
@returns {number} rounded value

@example
var v = trunc( -4.2 );
// returns -4.0

@example
var v = trunc( 9.99999 );
// returns 9.0

@example
var v = trunc( 0.0 );
// returns 0.0

@example
var v = trunc( -0.0 );
// returns -0.0

@example
var v = trunc( NaN );
// returns NaN

@example
var v = trunc( Infinity );
// returns Infinity

@example
var v = trunc( -Infinity );
// returns -Infinity