How do I differentiate this function?

Hi guys,

I am new to MATLAB and have the following problem: I programmed the following function

I took derivatives by hand but then I wanted MATLAB to take the derivatives for me with respect to independent variables K, NRC, X, R and NRM. Somehow I always get the following error message when using the diff function:

Error using sym/subsindex (line 769)
Invalid indexing or function definition. When defining a function, ensure that the arguments are symbolic
variables and the body of the function is a SYM expression. When indexing, the input must be numeric,
logical, or ':'.

Error in
@(K,NRC,NRM,R,X)Z*K^gamma((1-eta)*((1-alpha)*NRC^{EOS1}+alpha*(X^v+R^v)^{EOS1/v})^{EOS2/EOS1}+eta*NRM^{EOS2})^{(1-gamma)/EOS2}

Error in sym>funchandle2ref (line 1308)
    S = x(S{:});

Error in sym>tomupad (line 1206)
    x = funchandle2ref(x);

Error in sym (line 179)
                S.s = tomupad(x);

Error in sym/privResolveArgs (line 921)
                    argout{k} = sym(arg);

Error in sym/diff (line 21)
args = privResolveArgs(S,varargin{:});
 

By the way my code is the following:

>> gamma=0.3;
eta=0.11;
alpha=0.3;
v=0.6;
EOS2=0.00001;
EOS1=-1;
Z=1;
syms K NRC NRM R X


Y=@(K,NRC,NRM,R,X) Z*K^gamma((1-eta)*((1-alpha)*NRC^{EOS1}+alpha*(X^v+R^v)^{EOS1/v})^{EOS2/EOS1}+eta*NRM^{EOS2})^{(1-gamma)/EOS2};

partial1 = diff(Y,K);

What am I doing wrong?

Thanks for your answer!

Answer 1

[Torsten]

syms Z K gamma eta alpha NRC EOS1 v X R EOS2 NRM 
Y= Z*K^gamma*((1-eta)*((1-alpha)*NRC^EOS1+alpha*(X^v+R^v)^(EOS1/v))^(EOS2/EOS1)+eta*NRM^(EOS2))^((1-gamma)/EOS2);
dYdK = diff(Y,K)

[Leandro Nitsch]

Hi Torsten,

Thank you for your anwer. I did what you suggested but am still getting the same error message :/

[Torsten]

For me, the code as written works.