/**
* Get the lightning ratio ([0-1]).
*
* @param position the satellite's position in the selected frame.
* @param frame in which is defined the position
* @param date the date
* @return lightning ratio
* @exception OrekitException if the trajectory is inside the Earth
*/
public double getLightningRatio(
final Vector3D position, final Frame frame, final AbsoluteDate date) throws OrekitException {
// Compute useful angles
final double[] angle = getEclipseAngles(position, frame, date);
// Sat-Sun / Sat-CentralBody angle
final double sunEarthAngle = angle[0];
// Central Body apparent radius
final double alphaCentral = angle[1];
// Sun apparent radius
final double alphaSun = angle[2];
double result = 1.0;
// Is the satellite in complete umbra ?
if (sunEarthAngle - alphaCentral + alphaSun <= 0.0) {
result = 0.0;
} else if (sunEarthAngle - alphaCentral - alphaSun < 0.0) {
// Compute a lightning ratio in penumbra
final double sEA2 = sunEarthAngle * sunEarthAngle;
final double oo2sEA = 1.0 / (2. * sunEarthAngle);
final double aS2 = alphaSun * alphaSun;
final double aE2 = alphaCentral * alphaCentral;
final double aE2maS2 = aE2 - aS2;
final double alpha1 = (sEA2 - aE2maS2) * oo2sEA;
final double alpha2 = (sEA2 + aE2maS2) * oo2sEA;
// Protection against numerical inaccuracy at boundaries
final double a1oaS = FastMath.min(1.0, FastMath.max(-1.0, alpha1 / alphaSun));
final double aS2ma12 = FastMath.max(0.0, aS2 - alpha1 * alpha1);
final double a2oaE = FastMath.min(1.0, FastMath.max(-1.0, alpha2 / alphaCentral));
final double aE2ma22 = FastMath.max(0.0, aE2 - alpha2 * alpha2);
final double P1 = aS2 * FastMath.acos(a1oaS) - alpha1 * FastMath.sqrt(aS2ma12);
final double P2 = aE2 * FastMath.acos(a2oaE) - alpha2 * FastMath.sqrt(aE2ma22);
result = 1. - (P1 + P2) / (FastMath.PI * aS2);
}
return result;
}
public double execute(double in) throws DMLRuntimeException {
switch (bFunc) {
case SIN:
return FASTMATH ? FastMath.sin(in) : Math.sin(in);
case COS:
return FASTMATH ? FastMath.cos(in) : Math.cos(in);
case TAN:
return FASTMATH ? FastMath.tan(in) : Math.tan(in);
case ASIN:
return FASTMATH ? FastMath.asin(in) : Math.asin(in);
case ACOS:
return FASTMATH ? FastMath.acos(in) : Math.acos(in);
case ATAN:
return Math.atan(in); // faster in Math
case CEIL:
return FASTMATH ? FastMath.ceil(in) : Math.ceil(in);
case FLOOR:
return FASTMATH ? FastMath.floor(in) : Math.floor(in);
case LOG:
return FASTMATH ? FastMath.log(in) : Math.log(in);
case LOG_NZ:
return (in == 0) ? 0 : FASTMATH ? FastMath.log(in) : Math.log(in);
case ABS:
return Math.abs(in); // no need for FastMath
case SIGN:
return FASTMATH ? FastMath.signum(in) : Math.signum(in);
case SQRT:
return Math.sqrt(in); // faster in Math
case EXP:
return FASTMATH ? FastMath.exp(in) : Math.exp(in);
case ROUND:
return Math.round(in); // no need for FastMath
case PLOGP:
if (in == 0.0) return 0.0;
else if (in < 0) return Double.NaN;
else return (in * (FASTMATH ? FastMath.log(in) : Math.log(in)));
case SPROP:
// sample proportion: P*(1-P)
return in * (1 - in);
case SIGMOID:
// sigmoid: 1/(1+exp(-x))
return FASTMATH ? 1 / (1 + FastMath.exp(-in)) : 1 / (1 + Math.exp(-in));
case SELP:
// select positive: x*(x>0)
return (in > 0) ? in : 0;
default:
throw new DMLRuntimeException("Builtin.execute(): Unknown operation: " + bFunc);
}
}
@Override
public double getPartialSimilarity(double[] a, double[] b) {
final double lp = toHilbertPSpace(a, b);
// Per corner case condition
if (lp >= getSigma()) return 0.0;
final double twoOverPi = (2d / FastMath.PI);
final double lpOverSig = lp / getSigma();
/* Front segment */
final double front = twoOverPi * FastMath.acos(-lpOverSig);
/* Back segment */
final double first = twoOverPi * lpOverSig;
final double second = FastMath.sqrt(1.0 - FastMath.pow(lpOverSig, 2));
final double back = first * second;
final double answer = front - back;
return Double.isNaN(answer) ? Double.NEGATIVE_INFINITY : answer;
}
