Undefined function or method 'minus' for input arguments of type 'struct'

I create a function file that consist of

function f = ASM_1(x,xi,uH,Ks,KOH,KNO,ng,KNH,KOA,bH,bA,Ka,Kh,nh,Yh,Ya,fp,iXB,iXP,Kx,uA)

..........

f(1)=xi(1)-x(1);

........

f(9)=xi(9)-x(9)+(-1*iXB*p1)-(iXB*p2)+(-1*iXB-1/Ya)*p3+p6;

f(10)=xi(10)-x(10)-p6+p8;

f(11)=xi(11)-x(11)+(iXB-fp*iXP)*p4+(iXB-fp*iXP)*p5-p8;

end

then, i create another file

clc;

clear; 

fun = @ASM_1;

xi = [1,1,1,1,1,1,1,1,1,1,1];

x0 = [1,1,1,1,1,1,1,1,1,1,1];

[x,fval,exitflag,output] = fsolve(fun,xi,x0)

I run the program but it shows

??? Undefined function or method 'minus' for input arguments of
type 'struct'.

Error in ==> ASM_1 at 47
f(1)=xi(1)-x(1);

Error in ==> fsolve at 254
            fuser = feval(funfcn{3},x,varargin{:});

Error in ==> root2dd at 8
[x,fval,exitflag,output] = fsolve(fun,xi,x0,options)

Caused by:
    Failure in initial user-supplied objective function
    evaluation. FSOLVE cannot continue.

I have no idea how to solve this. Please help if you have any idea. Thanks

Answer 1

[Walter Roberson]

You defined ASM_1 as a function with 21 parameters. You defined fun as @ASM_1 which is a direct function handle, so fun needs to be passed 21 parameters.

fun is a function that accepts a vector x and returns a vector F, the nonlinear equations evaluated at x

so fsolve() will be passing only 1 parameter, a vector, to your function that expects 21 parameters. Where are you expecting xi, uH, Ks and so on to come from?

[chinhui ooi]

Sorry, I forgot to mention, those other parameters, xi,uH,Ks,KOH,KNO,ng,KNH,KOA,bH,bA,Ka,Kh,nh,Yh,Ya,fp,iXB,iXP,Kx,uA

they have its own value. Is that the cause of my problem?

[Walter Roberson]

How are you expecting them those values to reach the function? If they exist in the workspace and you want them to reach the function then you need

[x,fval,exitflag,output] = fsolve(@(x)ASM_1(x,xi,uH,Ks,KOH,KNO,ng,KNH,KOA,bH,bA,Ka,Kh,nh,Yh,Ya,fp,iXB,iXP,Kx,uA), xi, x0)