function avercosf( x ) {
	return addon( x );
}
Computes the inverse versed cosine of a single-precision floating-point number (in radians).

@private
@param {number} x - input value
@returns {number} inverse versed cosine

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

@example
var v = avercosf( -3.141592653589793 / 2.0 );
// returns ~2.1783

@example
var v = avercosf( -3.141592653589793 / 6.0 );
// returns ~1.0742

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