Error Message Index out of bounds

I have the code below and am getting the following error.

Attempted to access C(2); index out of bounds because numel(C)=1.

any ideas why?

h=0.1 ;
k1=0.005;
k2=0.005; 
k3=0.1 ;

t=[0:h:200] ;
E(1)=10;
S(1)=100;
C(1)=0;
P(1)=0;

for i=1:numel(t)-1 

     %E
     e1=(k2*C(i)+k3*C(i)-k1*E(i)*S(i));
     e2=k2*[C(i)+(h*e1/2)]+k3*[C(i)+(h*e1/2)]-k1*[E(i)+(h*e1/2)]*[S(i)+(h*e1/2)]
     e3=k2*[C(i)+(h*e2/2)]+k3*[C(i)+(h*e2/2)]-k1*[E(i)+(h*e2/2)]*[S(i)+(h*e2/2)]
     e4= k2*[C(i)+(h*e3)]+k3*[C(i)+(h*e3)]-(k1*[E(i)+(h*e3)]*[S(i)+(e3*h)])

end 

plot(t,e)

[Matt J]

In future, please highlight your code and apply the

formatting button, as I have just done for you now.

Answer 1

[Matt J]

any ideas why?

Yes. C is a scalar, but you are indexing it in your loop at many C(i) as if it were a vector. You must decide what C is really supposed to be.

[Kyle]

i was just trying to indicate that the initial value for C is zero ( and the same for E S and P). is that not a valid way of going about it? do u have any suggestions on how to correctly code that?

[Matt J]

But your loop doesn't refer only to the initial value of C, it refers to other C(i) too, which you have not supplied.

Answer 2

[Kyle]

so the for loop actually had additional equations. ( i had thought, that if i isolated a set of the equations, i could figure out the concept of the code, w.o making it tedious . obviously that was incorrect.) the code is running now. but i keep getting "NaN" for a ton of my output. any idea why?

h=0.1 ; k1=0.005; k2=0.005; k3=0.1 ;

t=[0:h:200];
E(1)=10;
S(1)=100;
C(1)=0;
P(1)=0;

for i=1:numel(t)-1 

     %E
     e1=(k2*C(i)+k3*C(i)-k1*E(i)*S(i));
     e2= k2*[C(i)+(h*e1/2)]+k3*[C(i)+(h*e1/2)]-k1*[E(i)+(h*e1/2)]*[S(i)+(h*e1/2)];
     e3= k2*[C(i)+(h*e2/2)]+k3*[C(i)+(h*e2/2)]-k1*[E(i)+(h*e2/2)]*[S(i)+(h*e2/2)];
     e4= k2*[C(i)+(h*e3)]+k3*[C(i)+(h*e3)]-(k1*[E(i)+(h*e3)]*[S(i)+(e3*h)]);
     E(i+1)=E(i)+(e1+2*e2+2*e3+e4)/6;

     % For S 
     s1=k2*C(i) -k1*E(i)+S(i);
     s2=k2*[C(i)+(h*s1/2)]-k1*[E(i)*(h*s1/2)]*[S(i)*(h*s1/2)] ;
     s3=k2*[C(i)+(h*s2/2)]-k1*[E(i)*(h*s2/2)]*[S(i)*(h*s2/2)];
     s4=k2*[C(i)+(h*s3)]-k1*[E(i)*(h*s3)]*[S(i)*(h*s3)];
     S(i+1)=S(i)+(s1+2*s2+2*s3+s4)/6; 

     % For C
     c1=k1*E(i)*S(i)-k2*C(i)-k2*C(i)-k3*C(i);
     c2=[k1*[E(i)+(h*c1)]*[S(i)*(h*c1/2)]]-[k2*[C(i)*(h*c1/2)]]-[k2*[C(i)*(h*c1/2)]]-[k3*[C(i)*(h*c1/2)]];
     c3=[k1*[E(i)+(h*c2)]*[S(i)*(h*c2/2)]]-[k2*[C(i)*(h*c2/2)]]-[k2*[C(i)*(h*c2/2)]]-[k3*[C(i)*(h*c2/2)]];
     c4=[k1*[E(i)*(h*c3)]*[S(i)*(h*c3)]]-[k2*[C(i)*(h*c3)]]-[k2*[C(i)*(h*c3)]]-[k3*[C(i)*(h*c3)]];
     C(i+1)=C(i)+(c1*2*c2+2*c3+c4); 

     %For P
     p1= k3*C(i)
     p2=k3*[C(i)*(h*p1/2)];
     p3=k3*[C(i)*(h*p2/2)];
     p4=k3*[C(i)*(h*p3)];
     P(i+1)=P(i)+(p1*2*p2+2*p3+p4)

end 

plot(t,E) 
hold on 
plot(t,C)
plot(t,P)
plot(t,S)

[Matt J]

Use

>>dbstop if naninf

to see where they are being introduced.

[Image Analyst]

Your numbers are overflowing. Just look at some of them - they're huge. Eventually you reach infinity. What are you doing? Are you sure those are the right equations?