Index exceeds the number of array elements (1).

I am unable to spot why I am getting an error. Please help to resolve the error.

x1_rec(1)=x1(1);
x2_rec(1)=x2(1);
y1_rec(1)=y1(1);
y2_rec(1)=y2(1);
%value of constants
%a1=x1
a1=ksaix1(1);
a2=ksaix1(2);
a3=ksaix1(3);
a4=ksaix1(4);
a5=ksaix1(5);
a6=ksaix1(6);
a7=ksaix1(7);
a8=ksaix1(8);
a9=ksaix1(9);
a10=ksaix1(10);
a11=ksaix1(11);
a12=ksaix1(12);
a13=ksaix1(13);
a14=ksaix1(14);
a15=ksaix1(15);
a16=ksaix1(16);
a17=ksaix1(17);
a18=ksaix1(18);
a19=ksaix1(19);
a20=ksaix1(20);
a21=ksaix1(21);
a22=ksaix1(22);
a23=ksaix1(23);
a24=ksaix1(24);
a25=ksaix1(25);
a26=ksaix1(26);
a27=ksaix1(27);
a28=ksaix1(28);
a29=ksaix1(29);
a30=ksaix1(30);
a31=ksaix1(31);
a32=ksaix1(32);
%c=x2
c1=ksaix2(1);
c2=ksaix2(2);
c3=ksaix2(3);
c4=ksaix2(4);
c5=ksaix2(5);
c6=ksaix2(6);
c7=ksaix2(7);
c8=ksaix2(8);
c9=ksaix2(9);
c10=ksaix2(10);
c11=ksaix2(11);
c12=ksaix2(12);
c13=ksaix2(13);
c14=ksaix2(14);
c15=ksaix2(15);
c16=ksaix2(16);
c17=ksaix2(17);
c18=ksaix2(18);
c19=ksaix2(19);
c20=ksaix2(20);
c21=ksaix2(21);
c22=ksaix2(22);
c23=ksaix2(23);
c24=ksaix2(24);
c25=ksaix2(25);
c26=ksaix2(26);
c27=ksaix2(27);
c28=ksaix2(28);
c29=ksaix2(29);
c30=ksaix2(30);
c31=ksaix2(31);
c32=ksaix2(32);

h=0.1;   %step size
t=0:h:50;
%ode
p=@(t,x1_rec,y1_rec,x2_rec,y2_rec) a1+a2*x1_rec+a3*x2_rec+a4*y1_rec+a5*y2_rec+a6*x1_rec*x2_rec+a7*y1_rec*y2_rec+a8*x1_rec*y1_rec+a9*x1_rec*y2_rec+a10*x2_rec*y1_rec+a11*x2_rec*y2_rec+a12*x1_rec*x2_rec*y1_rec+a13*x1_rec*x2_rec*y2_rec+a14*x1_rec*y1_rec*y2_rec+a15*x2_rec*y1_rec*y2_rec+a16*x1_rec*x2_rec*y1_rec*y2_rec+a17*x1_rec^2+a18*x2_rec^2+a19*y1_rec^2+a20*y2_rec^2+a21*x1_rec^2*x2_rec+a22*x1_rec^2*y1_rec+a23*x1_rec^2*y2_rec+a24*x2_rec^2*x1_rec+a25*x2_rec^2*y1_rec+a26*x2_rec^2*y2_rec+a27*y1_rec^2*x1_rec+a28*y1_rec^2*x2_rec+a29*y1_rec^2*y2_rec+a30*y2_rec^2*x1_rec+a31*y2_rec^2*x2_rec+a32*y2_rec^2*y1_rec;
q=@(t,x1_rec,y1_rec,x2_rec,y2_rec) c1+c2*x1_rec+c3*x2_rec+c4*y1_rec+c5*y2_rec+c6*x1_rec*x2_rec+c7*y1_rec*y2_rec+c8*x1_rec*y1_rec+c9*x1_rec*y2_rec+c10*x2_rec*y1_rec+c11*x2_rec*y2_rec+c12*x1_rec*x2_rec*y1_rec+c13*x1_rec*x2_rec*y2_rec+c14*x1_rec*y1_rec*y2_rec+c15*x2_rec*y1_rec*y2_rec+c16*x1_rec*x2_rec*y1_rec*y2_rec+c17*x1_rec^2+c18*x2_rec^2+c19*y1_rec^2+c20*y2_rec^2+c21*x1_rec^2*x2_rec+c22*x1_rec^2*y1_rec+c23*x1_rec^2*y2_rec+c24*x2_rec^2*x1_rec+c25*x2_rec^2*y1_rec+c26*x2_rec^2*y2_rec+c27*y1_rec^2*x1_rec+c28*y1_rec^2*x2_rec+c29*y1_rec^2*y2_rec+c30*y2_rec^2*x1_rec+c31*y2_rec^2*x2_rec+c32*y2_rec^2*y1_rec;
%loop
for i=1:(length(t)-1)
    k1=p(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));
    l1=q(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));
 
    
    k2=p(t(i)+h/2,(x1_rec(i)+(h/2)*k1),(y1_rec(i)+(h/2)*l1),(x2_rec(i)+(h/2)*k1),(y2_rec(i)+(h/2)*l1));
    l2=q(t(i)+h/2,(x1_rec(i)+(h/2)*k1),(y1_rec(i)+(h/2)*l1),(x2_rec(i)+(h/2)*k1),(y2_rec(i)+(h/2)*l1));
      
    k3=p(t(i)+h/2,(x1_rec(i)+(h/2)*k2),(y1_rec(i)+(h/2)*l2),(x2_rec(i)+(h/2)*k2),(y2_rec(i)+(h/2)*l2));
    l3=q(t(i)+h/2,(x1_rec(i)+(h/2)*k2),(y1_rec(i)+(h/2)*l2),(x2_rec(i)+(h/2)*k2),(y2_rec(i)+(h/2)*l2));
      
    k4=p(t(i)+h,(x1_rec(i)+k3*h),(y1_rec(i)+l3*h),(x2_rec(i)+k3*h),(y2_rec(i)+l3*h));
    l4=q(t(i)+h,(x1_rec(i)+k3*h),(y1_rec(i)+l3*h),(x2_rec(i)+k3*h),(y2_rec(i)+l3*h));
    
      x1_rec(i+1) = x1_rec(i) + h*(k1+2*k2+2*k3+k4)/6;
      %y1(i+1) = y1(i) + h*(l1+2*l2+2*l3+l4)/6;
      x2_rec(i+1) = x2_rec(i) + h*(k1+2*k2+2*k3+k4)/6;
      %y2(i+1) = y2(i) + h*(l1+2*l2+2*l3+l4)/6;
end
plot(x1_rec(1:length(x1)),'r','LineWidth',2)
plot(x2_rec(1:length(x2)),'r','LineWidth',2)


%%%%%Error%%%%

Index exceeds the number of array elements (1).

Error in coup (line 333)
    k1=p(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));

Answer 1

[KSSV]

The error is clear...you are trying to extract more number of elements than present int he array.

A = rand(1,10) ; 
A(1)    % no error 
A(5)    % no error 
A(end)  % no error 
A(11)   % error, as there is no 11th element 

Your code is very long and also you are accessing some local data in between which we don't have access to. So we cannot help you exact on the point. But the error occurs due to the reason mentioned above.

[Stephan]

To figure out whats wrong in detail you can use the little arrow at the "RUN" button in the Matlab Editor and activate "Pause on errors". Then the code stops at the point and you can check the workspace for the variable who causes the problem.

[Heya :)]

Can you spot where exactly is the mistake?

[Stephan]

Matlab tells you:

Error in coup (line 333)
    k1=p(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));

If you use the option i mentioned you can check whcih value has i in the moment the error appears and what are the lengths of t, x1_rec, y1_rec, x2_rec, y2_rec.

This should be enough information to understand whats going wrong.

[Heya :)]

Is their a way to change the size of x1_rec, y1_rec, x2_rec, y2_rec?

x1_rec(1)=x1(1);

x2_rec(1)=x2(1);

y1_rec(1)=y1(1);

y2_rec(1)=y2(1);

[KSSV]

You have messed up with your code at lot of places.

[Heya :)]

That is why i am here asking for help

Answer 2

[Nora Khaled]

can't run your code because it need to open file.

But check the sizes x1_rec, y1_rec, x2_rec, and y2_rec.

it seems that you the for loop exceed the number of elements.

[Heya :)]

I checked the size. It's same for four of them

[Nora Khaled]

are they equal to the size of t ?

cause matlab says its in line 333

Error in coup (line 333)
    k1=p(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));

so you should check here..

for i=1:(length(t)-1)
    k1=p(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));
    l1=q(t(i),x1_rec(i),y1_rec(i),x2_rec(i),y2_rec(i));
 

[Heya :)]

I checked and they are not equal to the size of t.

t is 1 1

x1_rec, y1_rec, x2_rec, and y2_rec are 1 6

[Heya :)]

How to adjust the size of t?

[Nora Khaled]

This does not seem right...

you have in line 326 and 327

h=0.1;   %step size
t=0:h:50;

so, t should be

 size(t)

ans =

     1   501

meaning that the loop will be form 1 to 500.

[Heya :)]

Yes you are right. How to adjust the size?

[KSSV]

so use linspace:

t = linspace(0,50,50) ; 

Or run the loop index upto length of t.

[Heya :)]

You mean this for i=1:(length(t))?