using optim function in different versions of Scilab

[Ivan Maximov]

Hi everyone!

I have a question what is confusing me. I use Scilab 4.1.2 under Linux (Fedora
10) and try to set up a optim function in the code below - but always get an
error message. However, in Scilab 5.1.1 it works without any messages (the
question does it work properly is still open). Could someone, please, explain
for me what is a problem in optim application in my code? 

Thanks a lot in advance.
Ivan

//-----------------------------------------------------------------------------------------------
funcprot(0);

function [y1,y2,y3,y4]=prop(x1,x2,x3,x4,ix,iy,sx,sy,dt,A,U,B,PROP,l1)

  y1 = x1;
  y2 = x2;
  y3 = x3;
  y4 = x4;

  N=length(x1)+1;

  for j=2:N
    
    HAMo = rand(4,4);
    B=rand(4,4);
    U=rand(4,4);

      function [yN]=fun(x)
        yN= -(2*real(trace(((expm(-%i*dt*HAMo)'*expm(-%i*dt*(x(1)*ix+x(2)*iy+x
		(3)*sx+x(4)*sy))- eye(4,4))*A*U*B*A') ))-dt*l1*((x(1)-x1(j-1)).*
		(x(1)+x1 (j-1)) +(x(2)-x2(j-1)).*(x(2)+x2(j-1))+(x(3)-x3(j-1)).*
		(x(3)+x3 (j-1)) +(x(4)-x4 (j-1)).* (x(4)+x4(j-1)))); 
     endfunction
    function [d_yN] =d_fun(x) 
	d_yN=derivative (fun,x); 
    endfunction
      
    function [yN,grd,ind]=f(x,ind)
        yN=fun(x);
        grd=d_fun(x);
    endfunction
	   
    x0= [x1(j-1);x2(j-1);x3(j-1);x4(j-1)];
   printf("BEFORE: %f\n",fun(x0));
	 [fopt,xN]=optim(f,x0);
  printf("AFTER: %f\n",fun(xN));
	 y1(j-1)	= xN(1);
	 y2(j-1)	= xN(2);
	 y3(j-1)	= xN(3);
	 y4(j-1)	= xN(4);
	  
  end

endfunction

x_pauli=[0,0.5;0.5,0]; 
y_pauli=[0,-0.5*%i;0.5*%i,0]; 
z_pauli=[0.5,0;0,-0.5];
u_pauli=[1,0;0,1];

J = 140;
T = 1/J;  N=10;  NIT=5;
dt=T/N;
rf = 100;
l1 = 1e-4;

//---------------------------------------------------------------------------
ix = x_pauli.*.u_pauli; iy = y_pauli.*.u_pauli; iz = z_pauli.*.u_pauli;
sx = u_pauli.*.x_pauli; sy = u_pauli.*.y_pauli; sz = u_pauli.*.z_pauli;
//---------------------------------------------------------------------------
Hamilt=2*%pi*J*sz*iz;
A=expm(-%i*0.5*dt*Hamilt);

U = rand(4,4);
B = rand(4,4);
PROP=rand(4,4);
//---------------------------------------------------------------------------
u1 = rf*rand(1,N-1); u2 = rf*rand(1,N-1);
u3 = rf*rand(1,N-1); u4 = rf*rand(1,N-1);

[y1,y2,y3,y4]=prop(u1,u2,u3,u4,ix,iy,sx,sy,dt,A,U,B,PROP,l1);