Failure in initial user-supplied objective function evaluation

I am trying to find the roots of a system of two equations with two variables and want to find the solution for different values of one of the parameters that is 'Dr'. As a start I created an .m file for the functions as

function F = root(x)

%parameters 

global mh mv dha dhc qa pa qc pc bvh bhav bhcv na zeta sh sv Dr

%equations
F = [(x(2)*x(1)+mh*qa*pa-(mh+dha+na+zeta))*(X(2)*x(1)-(mh+dhc))*(Dr*((x(1)).^2)+x(2)*x(1)-mv)-mh*qc*pc*zeta*(Dr*((x(1)).^2)+x(2)*x(1)-mv)+bvh*(sv/sh)*(bhcv*zeta-bhav*(x(2)*x(1)-(mh+dhc)));
x(2).*(x(2).*x(1)-1.2).*(0.2*(x(1).^2)+x(2).*x(1)-1.2)+(x(2).*x(1)-1.993).*x(2).*(0.2*(x(1).^2)+x(2).*x(1)-1.2)+(x(2).*x(1)-1.993).*(x(2).*x(1)-1.2).*(.4*x(1)+x(2))-0.00336*x(1)-1.251691869*x(2)];

end

Then I recalled it in a separate file with this codes

clear 
close all

global  mh mv dha dhc qa pa qc pc bvh bhav bhcv na zeta sh sv Dr; 

%parameters 

mh=.7;  mv=1.2;  dha=0.2; dhc=0.5;  
qa=0.1; pa=0.1; 
qc=0.3; pc=0.1; na=0.7;   zeta=.4; 
bvh= 3; bhav=.2; bhcv=2.6 sh=426.87; 
sv=884.57; 
Dr=0.2;

x0 = [-10 -10];
[x,fval] = fsolve(@root,x0);

I don't know what is the problem! I tried different initial values for x0 but keep getting the same error.

Answer 1

[Stephan]

Hi,

function myfun

     %parameters 
     mh=.7;
     mv=1.2; 
     dha=0.2; 
     dhc=0.5;
     qa=0.1;
     pa=0.1; 
     qc=0.3;
     pc=0.1;
     na=0.7; 
     zeta=.4; 
     bvh= 3;
     bhav=.2; 
     bhcv=2.6; 
     sh=426.87; 
     sv=884.57; 
     Dr=0.2;

     x0 = [-2.25 0.5]; 
     [x,fval] = fsolve(@root,x0)

      function F = root(x)
          %equations
          F = [(x(2)*x(1)+mh*qa*pa-(mh+dha+na+zeta))*(x(2)*x(1)-(mh+dhc))*(Dr*((x(1)).^2)+x(2)*x(1)-mv)-mh*qc*pc*zeta*(Dr*((x(1)).^2)+x(2)*x(1)-mv)+bvh*(sv/sh)*(bhcv*zeta-bhav*(x(2)*x(1)-(mh+dhc)));... 
          x(2).*(x(2).*x(1)-1.2).*(0.2*(x(1).^2)+x(2).*x(1)-1.2)+(x(2).*x(1)-1.993).*x(2).*(0.2*(x(1).^2)+x(2).*x(1)-1.2)+(x(2).*x(1)-1.993).*(x(2).*x(1)-1.2).*(.4*x(1)+x(2))-0.00336*x(1)-1.251691869*x(2)];    
      end
  end

Save this script with the same name of the outer function (here myfun).

In the equation of your objective function there was one X(2) instead of x(2). Since i like it better to use a nested function here, i killed your global variables...

Next Time you get an error message please provide the whole red text. Makes helping easier.

Also note the x0 values i have choosen and compare the results to your x0.

Best regards

Stephan

[AHUOD ALSHERI]

Thank you it worked.