Why is the FOR loop in my program producing empty matrices?

I am having a problem running a spiking-neuron simulator. I keep getting the error message, "operation +: Warning adding a matrix with the empty matrix will give an empty matrix result." Now I'm writing this program in "Scilab," but I'm hoping the problem I am having will be clear for the educated eye regardess. What I am doing is converting an existing MATLAB program to Scilab. The original MATLAB program and an explanation can be found here: https://www.izhikevich.org/publications/spikes.pdf

What happens in my Scilab version is that the first pass through the loop produces all the expected values. I Know this becuase I hit pause at the end of the first run, right before "end," and check all the values and matrix elements. However, if I run the program proper, which includes a loop of 20 iterations, I get the error message above, and all of the matrix values are empty! I cannot figure out what the problem is. I am fairly new to programming so the answer may be very simple as far as I know. Here is the Scilab version of the program:

Ne=8; Ni=2;
re=rand(Ne,1); ri=rand(Ni,1);

a=[0.02*ones(Ne,1); 0.02+0.08*ri];
b=[0.2*ones(Ne,1); 0.25-0.05*ri];
c=[-65+15*re.^2; -65*ones(Ni,1)];
d=[8-6*re.^2; 2*ones(Ni,1)];
S=[0.5*rand(Ne+Ni,Ne), -rand(Ne+Ni,Ni)];

v=60*rand(10,1)
v2=v
u=b.*v;
firings=[];

for t=1:20
    
    I=[5*rand(Ne,1,"normal");2*rand(Ni,1,"normal")];
    fired=find(v>=30);
    
    
    j = length(fired);
    h = t*ones(j,1);
    k=[h,fired'];
    
    firings=[firings;k];
    
    
    v(fired)=c(fired);
    u(fired)=u(fired)+d(fired);
    
    I=I+sum(S(:,fired),"c");
    
    v=v+0.5*(0.04*v.^2+5*v+140-u+I);
    v=v+0.5*(0.04*v.^2+5*v+140-u+I);
    
    u=u+a.*(b.*v-u);
    
end
plot(firings(:,1), firings(:,2),".");

Answer 1

[Sulaymon Eshkabilov]

Here is a bit edited and revised version of your code:

Ne=8; Ni=2;
re=rand(Ne,1); ri=rand(Ni,1);
a=[0.02*ones(Ne,1); 0.02+0.08*ri];
b=[0.2*ones(Ne,1); 0.25-0.05*ri];
c=[-65+15*re.^2; -65*ones(Ni,1)];
d=[8-6*re.^2; 2*ones(Ni,1)];
S=[0.5*rand(Ne+Ni,Ne), -rand(Ne+Ni,Ni)];
v=60*rand(10,1);
v2=v;
u=b.*v;
firings=[];
for t=1:20
    
    I=[5*randn(Ne,1);2*rand(Ni,1)];
    fired=find(v>=30);
        
    j = length(fired);
    h = t*ones(j,1);
    k=[h,fired];
    
    firings=[firings;k];
            
    v(fired)=c(fired);
    u(fired)=u(fired)+d(fired);
    
    I=I+sum(S(:,fired),"all");
    
    v=v+0.5*(0.04*v.^2+5*v+140-u+I);
    v=v+0.5*(0.04*v.^2+5*v+140-u+I);
    u=u+a.*(b.*v-u);  
end
plot(firings(:,1), firings(:,2),"ro", 'markerfacecolor', 'y');

[ray noack]

I appreciate the effort, Sulaymon, but that did not help. Are you running that program on Scilab? Becuase it is not running on my editor. For example, Scilab does not use "randn," as you entered it. It needs to be substituted with rand("normal"), etc.