You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: propMapFitGetZDeriv.m
    path of file: ./repos/LADAC/propulsion/propeller_map-based
    
    the code of the file until where you have to start completion: function Z_du = propMapFitGetZDeriv( prop_fit, RPM, V, output_name, ...
    deriv_name, is_extrap )
% PROPMAPFITGETZDERIV get propeller map fit output partial derivative
%   The outputs of the propeller map (thrust, torque or power) can be
%   derived w.r.t. the inputs RPM and V at the specified operating point.
% 
% Syntax:
%   Z = propMapFitGetZDeriv( prop_fit, RPM, V, output_name )
% 
% Inputs:
%   prop_fit                propeller map fit (struct) as defined by the
%                           function propMapFitCreate
%   RPM                     propeller rotational speed (NxM array), in rpm
%   V                       airspeed (NxM array), in m/s
%   output_name             name of the desired output quantity (string):
%                               'thrust' or
%                               'torque' or
%                               'power'
%   deriv_name              name of the variable (string); partial

    
function Z_du = propMapFitGetZDeriv( prop_fit, RPM, V, output_name, ...
    deriv_name, is_extrap )
% PROPMAPFITGETZDERIV get propeller map fit output partial derivative
%   The outputs of the propeller map (thrust, torque or power) can be
%   derived w.r.t. the inputs RPM and V at the specified operating point.
% 
% Syntax:
%   Z = propMapFitGetZDeriv( prop_fit, RPM, V, output_name )
% 
% Inputs:
%   prop_fit                propeller map fit (struct) as defined by the
%                           function propMapFitCreate
%   RPM                     propeller rotational speed (NxM array), in rpm
%   V                       airspeed (NxM array), in m/s
%   output_name             name of the desired output quantity (string):
%                               'thrust' or
%                               'torque' or
%                               'power'
%   deriv_name              name of the variable (string); partial
%                           derivative will be computed w.r.t. this
%                           variable:
%                               'RPM' or
%                               'V'
%   is_extrap               (optional) if the operating point is outside of
%                           the map data, should be extrapolated (true) or
%                           clipped (false) (bool); default is false
% 
% Outputs:
%   Z_du                    partial derivative of the specified input 
%                           output_name w.r.t. the specified input 
%                           deriv_name (NxM array), in N/rpm or Nm/rpm or
%                           W/rpm or N/(m/s) or Nm/(m/s) or W/(m/s)
% 
% See also:
%   PROPMAPFITCREATE, PROPMAPFITPLOT, PROPMAPFITGETZ
 
% Disclamer:
%   SPDX-License-Identifier: GPL-3.0-only
% 
%   Copyright (C) 2020-2022 Yannic Beyer
%   Copyright (C) 2022 TU Braunschweig, Institute of Flight Guidance
% *************************************************************************

if nargin < 6
    is_extrap = false;
end