Index in position 1 exceeds array bounds (must not exceed 1)?

When i run my program i get the error "Index in position 1 exceeds array bounds (must not exceed 1)." the error points to the line where i have put the arrow.

I assume the error is related to my v but i dont seem to get the error fixed. Any help would be appreciated

Thanks!

v=[];
v(1:4,1)=0;
for i=1:length(alpha)
    steg=alpha(i)*hmax;
    t=0:steg:T;
    for n=1:(T/steg)
->        v(1:4,n+1)=(idenmat-(steg*theta*A))\(v(1:4,n)+(steg*theta*(quartercar(t(n),v(1:4,n),A,nyak2,c2,m2,H,L,v)+roadprofile(H,L,v,t(n+1),nyak2))));
    end
end

[per isakson]

It's easier to debug code like yours if one

• use intermediary variables to breaks the long expression into smaller expressions.
• can run the code, which requires a realistic set of variable values ( alpha, hmax, etc.)

[Abdirahman Mohamed]

Sorry here is the complete version of my code:

I have done my best to condense the expression in the second for loop

clear
clc
close all

theta=0.5;
alpha=[];
alpha=[1, 10, 100];
v=[];
v(1:4,1)=0; %initial villkor
steg=0;
T=0.5;
t=[];

m1=460; m2=60; k1=5500;k2=130000; c1=300; c2=1300; v=60/3.6;
H=0.2; L=1;
nyak2=100*k2;
A = [0 0 1 0;0 0 0 1;-k1/m1 k1/m1 -c1/m1 c1/m1;k1/m2 -(k1+nyak2)/m2 c1/m2 -(c1+c2)/m2];

eigen=eig(A); %egenvärde för matrisen B
for i=1:4
    emax(i)=-2*real(eigen(i))/(norm(eigen(i))^2);
end

hmax=min(emax); %nya maximala tidssteget

options=odeset('RelTol',1e-9,'AbsTol',1e-9,'Refine',1);

idenmat=[1 0 0 0;0 1 0 0; 0 0 1 0; 0 0 0 1];

for i=1:length(alpha)
    steg=alpha(i)*hmax;
    t=0:steg:T;
    for n=1:(T/steg)
        v(1:4,n+1)=(idenmat-(steg*theta*A))\(v(1:4,n)+(steg*theta*(quartercar(t(n),v(1:4,n),A,nyak2,c2,m2,H,L,v)+roadprofile(H,L,v,t(n+1),nyak2))));
    end
end

Answer 1

[per isakson]

I replaced the inner for-loop by

        for n=1:(T/steg)
            f01 = idenmat - steg*theta*A;
            f22 = quartercar( t(n), v(1:4,n), A, nyak2, c2, m2, H, L, v );
            f23 = roadprofile( H, L, v, t(n+1), nyak2 );
            tmp = f01 \ (v(1:4,n)+(steg*theta*( f22 + f23 ) ) );
            %
            v(1:4,n+1)=(idenmat-(steg*theta*A))\(v(1:4,n)+(steg*theta*(quartercar(t(n),v(1:4,n),A,nyak2,c2,m2,H,L,v)+roadprofile(H,L,v,t(n+1),nyak2))));
        end

to make it easier to spot the error and inspect variable values. (My variable names indicate lack of fantacy. )

Next, I turned your script into a function

function cssm
    % your script
end

to avoid litter my base workspace (and because I prefer functions)

Next, I enabled Pause on Errors (in the Run menu)

And clicked Run. The execution halted on the line

f22 = quartercar( t(n), v(1:4,n), A, nyak2, c2, m2, H, L, v );

Hovering with the cursor over v(1:4,n) showed that the value of v is a scalar. v is assigned the scalar value at the line

m1=460; m2=60; k1=5500;k2=130000; c1=300; c2=1300; v=60/3.6;