Index exceeds matrix dimensions error !!

I am using newton -raphson method .. the code for newton method is ..

function [x,f,ea,iter] = newtmult (func,x0,es,maxit,varargin)

if nargin<2,error('atleast 2 input arguments required'),end

if nargin<3||isempty(es),es=0.0001;end

if nargin<4||isempty(maxit),maxit=50;end

iter = 0;

x = x0;

while (1)

      [J,f] = func(x,varargin{:});
      [L,U] = lu(J);
      dx = U\(L\f); 
      x = x - dx;
      iter = iter+1;
      ea = 100*max(abs(dx./x));
      if iter>=maxit||ea<=es, break, end
  end

Using this function i am supposed to calculate the values of some variables of other code .. which is as follows :

% open circuit voltage irradiance and temperature dependence
% Voc1 = is the irradiance dependent Voc 
% Voc2 = is the temperature dependent Voc 
% Voc1 has to be calculated using Newton -Raphson method. 
function [J,f] = Voccalculation4(x,varargin)
%v = [ Voc1 Voc2]
Rsh =   417.5; % panel parallel (shunt) resistance.
Ns = 72 ; % no of cells connected in series.
Iph = 5.20;
I0 = 4.54;
G = 1000 ;  % G= irradiance (different values of irradiance ) in W/m^2.
Iph1 = Iph*G;   % Iph = photo-generated current in STC , obtained from previous calculation.
%I01 =  I0*G ; % I0 = dark saturation current in STC,obtained from previous calculation.
Tstc = 298 ;  % Tstc (K) is temperature in kelvin at STC .
K = 1.381e-23; %Boltzmann constant = 1.3806488 × 10-23 m2 kg s-2 K-1 .
q = 1.60e-19; % electron charge in coulombs.
A=1.2;
Vt = (A*K*Tstc)/q  ;   % threshold voltage of cell-diode.
Voc = 42;
T = 320 ; % operating range given in datasheet !
Kv = -0.38;
format short
% G is irradiance here
syms Voc1  Voc2

f1= Voc1 - (log((Iph1*Rsh - Voc1)/(I0*Rsh)))*Ns*Vt;

f2= Voc2 - Voc + Kv(T-Tstc); % sign before Kv is positive in standard equation.

J11 = diff(f1,'Voc1');

J12 = diff(f1,'Voc2');

J21 = diff(f2,'Voc1');

J22 = diff(f2,'Voc2');

f = zeros(2,1);

f(1)= subs (f1,{Voc1,Voc2},{x(1),x(2)});

f(2)= subs (f2,{Voc1,Voc2},{x(1),x(2)});

J = zeros(2,2);

J(1,1) = subs (J11,{Voc1,Voc2},{x(1),x(2)});

J(1,2) = subs (J12,{Voc1,Voc2},{x(1),x(2)});

J(2,1) = subs (J21,{Voc1,Voc2},{x(1),x(2)});

J(2,2) = subs (J22,{Voc1,Voc2},{x(1),x(2)});

J

I have been stuck on this code for weeks now ... after trying recommendations to other users .. I am finally posting it here .. any help will be greatly appreciated !!! Thanks in advance .

[Matt J]

Help with what? You haven't posted any error messages or described what isn't working.

[Matt J]

Guardian commented:

putting this in command prompt :

[x,f,ea,iter] = newtmult (@Voccalculation4,[42;42],0.01,2)

*the error I am getting is *

??? Index exceeds matrix dimensions.

Error in ==> Voccalculation4 at 30 f2= Voc2 - Voc + Kv(T-Tstc); % sign before Kv is positive in standard equation.

Error in ==> newtmult at 11 [J,f] = func(x,varargin{:});

Answer 1

[Matt J]

My guess is that you're missing a multiplication operator:

f2= Voc2 - Voc + Kv*(T-Tstc);

[Guardian]

oops thats a silly mistake to make !!! thanks for pointing out that .. after correction .. i am still getting an error as :

??? In an assignment A(I) = B, the number of elements in B and

 I must be the same.

Error in ==> Voccalculation4 at 42 f(2)= subs (f2,{Voc1,Voc2},{x(1),x(2)});

Error in ==> newtmult at 11 [J,f] = func(x,varargin{:});

[Matt J]

subs (f2,{Voc1,Voc2},{x(1),x(2)})

is not returning a scalar, as intended. The error is the kind of thing you get when you do this

    >> x=1:3

    x =

         1     2     3

    >> x(2)=eye(5)
    In an assignment  A(I) = B, the number of elements in B and I must be the same.

Answer 2

[Guardian]

Relocated to Comment by Matt J