having an error in a matlab code due to ' assignment A(I) = B, the number of elements in B and I must be the same.'

Hi every body, i have a problem in a matlab code, i need your help:

the function , i call is here: so my probleme is that i have this error , and i don't really understand:

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

function dy = dynamiquelaser(t,y)
  global to_c g_d alpha_h G_n  to_e n_sp phi_inj I_inj i
  dy = zeros(3,1);    % a column vector
  dy(1) =  (g_d/to_c)*y(3).*y(1) + 2*sqrt(y(1)*I_inj).*cos(phi_inj-y(2)) ;    
  dy(2) =  ((alpha_h*g_d)/(2*to_c))*y(3)   ;
  dy(3) =  (1/to_e)*(4.5-y(3)-((to_e*G_n.*y(1)).*((y(3))+(1/n_sp))));
  i=i+1 
end

 t=0:1e-12:3e-9;
 [T,Y] = ode45(@dynamiquelaser,t,[10 5 5]);

the script that call the function described previously

i have a problem in the line number one, this function, is used in program that resolve the system using the solver ODE 45, is there any syntax code error?

Thank you for your help

the different values of the numerical parameters if someone want to run the code

clc
clear all
close all
global to_c g_d alpha_h G_n to_e n_sp gamma_c N_th  N_t to_p t i h c n lambda0 L e l omega0 w_inj
L = 200*1e-6; 
l = 3*1e-6  ;  
e = 0.15*1e-6;      
V = 9*1e-17;         
c = 3*1e8;                       
h = 1.054571726*1e-34;           
q = 1.60217656535*1e-19;         
lambda0=1500*1e-9;              
omega0=2*pi*c/lambda0;           
gamma_c= 0.05;                   
I_th = 10.5*1e-3;                
to_e = 181*1e-12;                
N_t =  1.77*1e21;                
N_th = 1.53*1e22;                
to_p = 10*1e-12;                 
G = 1.9*1e-18 ;               
G_n = 1.5*1e-10;                 
alpha_h = 6.5;                   
n = 3.8;                         
to_c =(2*n*L)/c;                 
g_d = gamma_c*G_n*N_th*to_c;     
n_sp  = N_th/( N_th - N_t);      
i=0;
t=0:1e-12:3e-9;
phi_inj=1e15;                     
I_inj=1e19;

Answer 1

[Walter Roberson]

You did not declare some variables as global in the defining routine.

Adjusted code is attached.

[yassine chafiq]

Thank You Walter Roberson, all works good, appreciate it!