function cdf( q ) {
		var probinic;
		var auxprob;
		var found;
		var a;
		if ( isnan( q ) ) {
			return NaN;
		}
		if ( q < 0.0 ) {
			return 0.0;
		}
		if ( q === PINF ) {
			return 1.0;
		}
		if (
			v > 25000 ||
			gausslegdquad( q, 0, r, nranges, -1.0, 1.0, 20, v, ll ) === 0
		) {
			return pow( prangeVInf( q, r ), nranges );
		}
		auxprob = 0;
		found = false;
		a = 0;
		probinic = 0;
		while ( !found ) {
			auxprob += gausslegdquad( q, a, r, nranges, -1.0, +1.0, 20, v, ll );
			if ( auxprob > 1.0 ) {
				return 1.0;
			}
			if ( abs(auxprob - probinic) / auxprob <= PRECISION ) {
				found = true;
			} else {
				probinic = auxprob;
			}
			a += 1;
		}
		return auxprob;
	}
Evaluates the cumulative distribution function (CDF) for a studentized range distribution.

@private
@param {number} q - quantile of the studentized range
@returns {Probability} evaluated CDF

@example
var y = cdf( 2.0 );
// returns <number>