public Matrix derivative(DirectPosition dp)
throws MismatchedDimensionException, TransformException {
PiecewiseUtilities.ensureNonNull("DirectPosition", dp);
PiecewiseUtilities.checkDimension(dp);
if(checkContainment(dp.getOrdinate(0)))
return new Matrix1(1);
throw new IllegalArgumentException(Errors.format(ErrorKeys.ILLEGAL_ARGUMENT_$1,"DirectPosition"));
}