Failure in initial objective function evaluation. FSOLVE cannot continue.

Hi all,

I'm trying to solve a non linear, parametric system of equations.

Here my myfun_driver.m file containing the call to the function with fsolve:

fun = @root7d;
x0 = [0,0];
x = fsolve(fun,x0);

Here the root7d.m file where I defined the function and parameters (the main function has a call to othe functions, I don't know if I'm doing well):

%parameters
Vp=100;
Kp=0.5;
q=1;
phi=0.006;
MIN=1;
N1=10;
gb=0.8;
gp=0.45;
g1=0.6;
g2=0.5;
g3=0.6;
gf=0.75;
arb=1-ar;
ar=0.2;
r1=0.8;
eps2=0.02;

rho = @(x,vp,kp,gp,gb,MIN,N1)( (1-gp)* vp*x(1)/(kp+x(1))...
    + (1-gb)* (MIN*exp(x(1)/N1)*x(2)));

G1 = @(x,ar,eps2)((ar*x(2)+(1-ar)*x(2))/(eps2^2 + (ar*x(2)+(1-ar)*x(2))^2));

function F = root7d(x,vp,kp,q,phi,r1,MIN,N1,gb,ar,arb)
F(1) = -vp*x(1)/(kp+x(1))*q*x(2) +q*rho(x,gp,gb) + phi - r1*MIN*exp(x(1)/N1)*x(2);
F(2) = gb*r1*MIN*exp(x(1)/N1)*x(2) - r1*G1(x,ar)*arb*x(2)/(ar*x(2)+(1-ar)*x(2));
end

I don't know why I obtain the following message: Failure in initial objective function evaluation. FSOLVE cannot continue.

Answer 1

[Torsten]

fun = @root7d;
x0 = [10,10];
x = fsolve(fun,x0)

Equation solved.

fsolve completed because the vector of function values is near zero
as measured by the value of the function tolerance, and
the problem appears regular as measured by the gradient.

x = 1×2

12.3661 0.5385

fun(x)

ans = 1×2

1.0e-12 * -0.2036 0.0266

function F = root7d(x)
  %parameters
  vp=100;
  kp=0.5;
  q=1;
  phi=0.006;
  MIN=1;
  N1=10;
  gb=0.8;
  gp=0.45;
  g1=0.6;
  g2=0.5;
  g3=0.6;
  gf=0.75;
  ar=0.2;
  arb=1-ar;
  r1=0.8;
  eps2=0.02;

  rho = ( (1-gp)* vp*x(1)/(kp+x(1)) + (1-gb)* (MIN*exp(x(1)/N1)*x(2)));

  G1 = ((ar*x(2)+(1-ar)*x(2))/(eps2^2 + (ar*x(2)+(1-ar)*x(2))^2));

  F(1) = -vp*x(1)/(kp+x(1))*q*x(2) +q*rho + phi - r1*MIN*exp(x(1)/N1)*x(2);
  F(2) = gb*r1*MIN*exp(x(1)/N1)*x(2) - r1*G1*arb*x(2)/(ar*x(2)+(1-ar)*x(2));
end

[sara]

So it depends on the initial conditions...