function secd( x ) {
	return 1.0 / cosd( x );
}
Computes the secant of an angle measured in degrees.

@param {number} x - input value (in degrees)
@returns {number} secant

@example
var v = secd( 30.0 );
// returns ~1.15

@example
var v = secd( 45.0 );
// returns ~1.41

@example
var v = secd( 60.0 );
// returns ~2.0

@example
var v = secd( 90.0 );
// returns Infinity

@example
var v = secd( 0.0 );
// returns 1.0

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