/// <inheritdoc/>
/// <exception cref="DimensionMismatchException"> if number of free parameters
/// or orders do not match</exception>
public DerivativeStructure linearCombination(DerivativeStructure[] a, DerivativeStructure[] b)
{
// compute an accurate value, taking care of cancellations
double[] aDouble = new double[a.Length];
for (int i = 0; i < a.Length; ++i)
{
aDouble[i] = a[i].getValue();
}
double[] bDouble = new double[b.Length];
for (int i = 0; i < b.Length; ++i)
{
bDouble[i] = b[i].getValue();
}
double accurateValue = MathArrays.linearCombination(aDouble, bDouble);
// compute a simple value, with all partial derivatives
DerivativeStructure simpleValue = a[0].getField().getZero();
for (int i = 0; i < a.Length; ++i)
{
simpleValue = simpleValue.add(a[i].multiply(b[i]));
}
// create a result with accurate value and all derivatives (not necessarily as accurate as the value)
double[] all = simpleValue.getAllDerivatives();
all[0] = accurateValue;
return(new DerivativeStructure(simpleValue.getFreeParameters(), simpleValue.getOrder(), all));
}
/// <inheritdoc/>
/// <exception cref="DimensionMismatchException"> if number of free parameters
/// or orders do not match</exception>
public DerivativeStructure linearCombination(double a1, DerivativeStructure b1, double a2, DerivativeStructure b2)
{
// compute an accurate value, taking care of cancellations
double accurateValue = MathArrays.linearCombination(a1, b1.getValue(),
a2, b2.getValue());
// compute a simple value, with all partial derivatives
DerivativeStructure simpleValue = b1.multiply(a1).add(b2.multiply(a2));
// create a result with accurate value and all derivatives (not necessarily as accurate as the value)
double[] all = simpleValue.getAllDerivatives();
all[0] = accurateValue;
return(new DerivativeStructure(getFreeParameters(), getOrder(), all));
}