code: @Override
  	public Complex apply(Complex argument) {
  		Complex iargument = argument.multiply(Complex.I);
  		Complex exponent = iargument.add(1.0);
  		Complex numerator = (new Complex(strike)).pow(exponent.subtract(1.0)).multiply(exponent);
  		Complex denominator = (argument.multiply(argument)).subtract(iargument);
  
  		return numerator.divide(denominator);
  	}
docs: /* (non-Javadoc)
  @see net.finmath.fouriermethod.CharacteristicFunctionInterface#apply(org.apache.commons.math3.complex.Complex)