Problem with Argument and fsolve

Hi everyone, I am trying to solve:

S= (50625*(arg(x*i + y - 1393 - 746*i) - 3560289735917593/36028797018963968)^2)/pi^2 + ((x + (y - 987)^2 - 24025)^(1/2)/2 - 8643/20)^2 + (3240000*(arg(x*i + y - 259 - 1571*i) + 8955599335723659/288230376151711744)^2)/(169*pi^2) + (90000*(arg(x*i + y - 375 - 629*i) - 3959779706285659/144115188075855872)^2)/pi^2
  end

with fsolve. But i am getting following error message:

'Undefined function 'arg' for input arguments of type 'double'.

Error in myfun (line 2)
F = [((x(1) + (x(2) - 987)^2 - 24025)^(1/2)/2 - 8643/20)/(2*(x(1) + (x(2) - 987)^2 - 24025)^(1/2)) -
(6480000*((17*pi)/60 + arg(x(1)*i + x(2) - 259 - 1571*i))*(imag(x(1)) - real(x(2)) + 259))/(169*pi
Error in fsolve (line 241)
            fuser = feval(funfcn{3},x,varargin{:});

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

Please help me out in this. Thanks

[Matt J]

You haven't told us (and apparently not FSOLVE either) what arg() is and where it comes from. We would need to see more of your code, in particular the definition of your function, where you define arg(), and your call to FSOLVE.

[satendra kumar]

Okay, Here is the full code:-

1. Defination of function. This is main file.

    if true

theta =([162.2, 45.1, 309]);
sigma =([.8, .6, 1.3, 2.0]);
X =([746, 629, 1571, 155]);
Y =([1393,375,259,987]);
d4 =864.3;

for j=1:3
    theta(j)=(2*pi*theta(j)/360);

      if theta(j)>(pi)
      theta(j)=theta(j)-(2*pi);
      end
  end

for j=1:3
    sigma(j)=(2*pi*sigma(j)/360);

      if sigma(j)>(pi);
      sigma(j)=sigma(j)-2*pi;
      end

end
theta
sigma

%%SUM of Squers 
syms x
syms y;
S=0;
for j=1:3
S=S+(((atan(x-X(j), y-Y(j))-theta(j)))/sigma(j))^2;
end
S=S+((((x-X(4)^2) + (y-Y(4))^2)^.5-d4)/sigma(4))^2

Sx=diff(S,x);
Sy=diff(S,y);
x0=[750 950];
[x fval]=fsolve(@myfun,x0)

    end

File for fsolve:

   if true
  function F = myfun(x)
  F = [ ((x(1) + (x(2) - 987)^2 - 24025)^(1/2)/2 - 8643/20)/(2*(x(1) + (x(2) - 987)^2 - 24025)^(1/2));
        (14664628646633870009187528867840000*real(x(2)))/452869728063427961323810153909 - (14664628646633870009187528867840000*imag(x(1)))/452869728063427961323810153909 + (((x(1) + (x(2) - 987)^2 - 24025)^(1/2)/2 - 8643/20)*(2*x(2) - 1974))/(2*(x(1) + (x(2) - 987)^2 - 24025)^(1/2)) - 5132948614190041913371008122974671477375/231869300768475116197790798801408;

          ];
  end

    end

[Shashank Prasanna]

Please format the code using the 'Code' button, it is very unreadable.

[satendra kumar]

Sorry for the inconvenience, Now i made it correct. Please look into it.

[Walter Roberson]

? Your current function has no reference to arg(). Are you possibly using matlabFunction() to generate the function in some code you have not shown here? The myfun() you have shown here has no relationship to finding S or Sx or Sy.

Answer 1

[Shashank Prasanna]

Satendra, arg is not a function in MATLAB but you the function 'angle' computes the argument of the complex number which I believe you are trying to find. In your 'S' replace 'arg' with 'angle'

http://www.mathworks.com/help/matlab/ref/angle.html

[satendra kumar]

Thanks Shashank, But when i did that i got following error message:

Undefined function 'atan2' for input arguments of type 'sym'.

Error in angle (line 14)
p = atan2(imag(h), real(h));