Header.HeaderData selectBody(string name)
{
for (int i = 0; i < this.header.numBodies; i++)
{
Header.HeaderData body = this.header.getBodyInfo(i);
if (name.Equals(body.getName()))
{
return(this.header.getBodyInfo(i));
}
}
throw new KeyNotFoundException("No body by the name " + name);
}
public Coordinate[] calculatePos(Body body, double jd)
{
File ephFile = selectFile(jd);
File.Block ephBlock = ephFile.getBlock(jd);
Header.HeaderData bodyInfo = selectBody(body.getName());
//this function gets the start and end times of the relevant block
double[] tRange = ephBlock.position(new int[2] {
0, 1
});
//then it scales our given time to a range the Chebyshev polynomials can accept and tells us which set to take
double[] scaledTime = scaler(jd, tRange[0], tRange[1], bodyInfo.getNumCoordinates());
//so the range we need to take is: [startpos-1+numCoefs*dimension*set, numCoefs*dimension]
double[] coefs = ephBlock.position(bodyInfo.getStart() - 1 + bodyInfo.getNumCoefficients() * ephFile.dimension * (int)scaledTime[0], bodyInfo.getNumCoefficients() * ephFile.dimension);
double[] position = Chebyshev.sequence(coefs, scaledTime[1], ephFile.dimension);
double[] velocity = Chebyshev.Dsequence(coefs, scaledTime[1], ephFile.dimension);
return(new Coordinate[2] {
new Coordinate(position), new Coordinate(velocity)
});
}
