// ----------- Numbers
@Override
protected ValueHolder evaluateNumber(final FormulaContext ctx, final ValueHolder[] params) {
Collection<double[]> values = new ParameterCollectionDouble(params, isPermutative);
ValueHolder ret = ValueHolder.createValueHolder(double.class, values.size());
for (double[] value : values) {
ret.add(computer.compute(value[0], value[1]));
}