function cdf( x, mu, s ) {
	return addon( x, mu, s );
}
Evaluates the cumulative distribution function (CDF) for a raised cosine distribution with location parameter `mu` and scale parameter `s` at a value `x`.

@private
@param {number} x - input value
@param {number} mu - location parameter
@param {NonNegativeNumber} s - scale parameter
@returns {Probability} evaluated CDF

@example
var y = cdf( 0.5, 0.0, 1.0 );
// returns ~0.909

@example
var y = cdf( 1.2, 0.0, 1.0 );
// returns 1.0

@example
var y = cdf( -0.9, 0.0, 1.0 );
// returns ~0.0

@example
var y = cdf( 2.0, 0.0, NaN );
// returns NaN

@example
var y = cdf( 2.0, NaN, 1.0 );
// returns NaN

@example
var y = cdf( NaN, 0.0, 1.0 );
// returns NaN