What does this error mean and how do I fix it?

I received the following error and am not sure how to correct it? I've copied my 3 function files below.

This thing is really beating me up!

 >> project2
Error using feval
Undefined function 'eqns' for input arguments of type 'double'.
Error in fsolve (line 218)
            fuser = feval(funfcn{3},x,varargin{:});
Error in project2 (line 42)
sol = fsolve(@eqns,[-100e-3 -80e-3])    % Solve for values of psid and psis
Caused by:
    Failure in initial user-supplied objective function evaluation. FSOLVE
    cannot continue.

Main Program:

 function y = project2(pH,ckcl)
 global  Eo Ef N F R T c0 c10 c20 c30 c40 z z1 z2 z3 z4 ka kb L W h u 
z = 1;
z1 = 1;
z2 = -1;
z3 = 1;
z4 = -1;
T = 300;
R = 8.314;
F = 96490;
Eo = 1;
Ef = 7.08e-10;
N = 1.3285e-5;
ka = 10^(-8+3);
kb = 10^(-2.5-3);
L = 4.5e-3;
W = 50e-6;
h = 200e-9;
u = 10e-3;
pH = 8;
Cckcl = logspace(0.1,500,100);
for i = 1:length(Cckcl)
    ckcl = Cckcl(i)
if pH<= 7
        c10 = 10^(-pH+3);
        c20 = ckcl;
        c30 = ckcl + 10^(-pH+3) - 10^(-(14-pH)+3);
        c40 = 10^(-(14-pH)+3);
        c0  = ckcl + 10^(-pH+3);
else
        c10 = 10^(-pH+3);
        c20 = ckcl + 10^(-pH+3) - 10^(-(14-pH)+3);
        c30 = ckcl;
        c40 = 10^(-(14-pH)+3);
        c0  = ckcl + 10^(-(14-pH)+3);
end
kaba = sqrt((Eo*Ef*R*T)/(2*z^2*F^2*c0));
sol = fsolve(@eqns,[-100e-3 -80e-3])    % Solve for values of psid and psis
psis = sol(1);
psid = sol(2);
psid_ckcl(i) = psid;
I = quadl(@finite,0,h/2)   % Solve for the integral of streaming current
G = (-W/u*L)*I;
G_ckcl(i) = G;
end 
plot(ckcl,psid_ckcl)    % Figure 1
plot(ckcl,G_ckcl)       % Figure 2

First function program (eqns):

 function y = eqns(psi)
global  N F R T c10 c20 c30 c40 z z1 z2 z3 z4 ka kb Eo Ef L W h kaba Cs psi
Cs = 0.3;
Hs = c30*exp(-F*psi(1)/(R*T));
sigs = -F*N*(ka-kb*Hs^2)/(ka+Hs+kb*Hs^2);
sigd = sign(psi(2))*sqrt(2*Ef*R*T*((c10*(-1*exp(-(z1*F*psi(2))/(R*T))))+(c20*(-1*exp(-(z1*F*psi(2))/(R*T))))+(c30*(-1*exp(-(z1*F*psi(2))/(R*T))))+(c40*(-1*exp(-(z1*F*psi(2))/(R*T))))));
y(1) = Cs*(psid - psis) + sigs;
y(2) = -Cs*(psid - psis) - sigd;

Second function program (finite):

 function y = finite(x)
global psid kaba h c10 c20 c30 c40 z1 z2 z3 z4 F R T
temp1 = 1+exp(x*-kaba) * tanh(F*psid/4*R*T);
temp2 = 1-exp(x*-kaba) * tanh(F*psid/4*R*T);
psi = 2*R*T/F * log(temp1./temp2);
pe = F*(z1*c10*exp(-z1*F/R*T*psi)+z2*c20*exp(-z2*F/R*T*psi)+z3*c30*exp(-z3*F/R*T*psi)+z4*c40*exp(-z4*F/R*T*psi));
y = pe.*(x.^2 - h*x);
end

[Walter Roberson]

eqns must be stored in eqns.m and on the MATLAB path, or it must be stored as part of the same file that uses it (the one holding project2)

At the command prompt, give the command

which -all eqns

and see what shows up.

[Aaron]

It shows me the path:

 >> which -all eqns
E:\Comp. Methods\Course Project 2\Project 2 revision\eqns.m

[Walter Roberson]

At the command prompt, try

eqns(0)

and see if it can find eqns or not.