unable to perform assignment becuase the left and right sides have a different amount of elements HELPPP!!

f1=@(x,y1,y2) (-6*y2-5*y1)/.5
f2=@(x,y1,y2) diff(y1)


% Condiciones iniciales -----------------------------------------------
%y1(0)=1;
%y2(0)=0;

x=0
xn=5
y1=1
y2=0
h=0.5

% Método de RK4Orden ---------------------------------------------------
while x(end)<=xn
    k11= f1(x(end),y1(end),y2(end)); 
    k12= f2(x(end),y2(end),y2(end)); 
    k21= f1(x(end)+.5*h,y1(end)+.5*k11*h,y2(end)+.5*k12*h);
    k22= f2(x(end)+.5*h,y1(end)+.5*h*k11,y2(end)+.5*h*k12);
    k31= f1(x(end)+.5*h,y1(end)+.5*k21*h,y2(end)+.5*k22*h);
    k32= f2(x(end)+.5*h,y2(end)+.5*k22*h,y2(end)+.5*k22*h);
    k41= f1(x(end)+h,y1(end)+k31*h,y2(end)+k32*h);
    k42= f2(x(end)+h,y2(end)+k32*h,y2(end)+k32*h);
    x(end+1)=x(end)+h;
    y1(end+1)=y1(end)+1/6*(k11+2*k21+2*k31+k41)*h;    
    y2(end+1)=y2(end)+1/6*(k12+2*k22+2*k32+k42)*h;   
end
plot(x,y1)

[DGM]

You start out with this:

k12= f2(x(end),y2(end),y2(end)); 

Which is essentially doing

diff(0)

and so returns an empty vector. As a consequence, all the other kxx constants are empty vectors.

[LG]

so what should i do??

i changed it to k12=f2(x(end),y1(end),y2(end)) and it is still not working, same error

[Walter Roberson]

You follow the guidance I gave at https://www.mathworks.com/matlabcentral/answers/1741615-why-is-it-not-plotting-or-graph-it-comes-out-blank#answer_986690

[Jeffrey Clark]

Two more lines like k12 need fixing:

k32= f2(x(end)+.5*h,y2(end)+.5*k22*h,y2(end)+.5*k22*h);
k42= f2(x(end)+h,y2(end)+k32*h,y2(end)+k32*h);