MATLAB: Error: ()-indexing must appear last in an index expression

cell indexingerror: ()-indexing must appear last in an index expressionMATLAB

I m getting this error while i try to execute this code

for i=1:n

    for j=1:n
        b1=bu(1,i)(j);
        a1=(n*b1/(m(i)*m(j)));
        p{1,i}=a1;
    end
end

here bu is a cell of size(1,n)

m is an array of size(1,n)

p is i a cell of size(1,n)

please help

Thanks in advance!

Best Answer

I'm guessing you want:

for i=1:n
    for j=1:n
        b1=bu{i}(j);
        a1=(n*b1/(m(i)*m(j)));
        p{i}=a1;
    end
end

Related Solutions

MATLAB: Preallocate an matrix in 2 for loops

N=numel(A);
B=zeros(N,N); %This is how
for j=1:N
    for i=1:N
        B(j,i)="Calculation here"
    end
end

MATLAB: How to take 100 samples of a plot.

First, what are you actually doing with M, Xdot1, etc.? Currently, the code overwrites them each N_m loop, without doing anything with the results

Try this: define sampled vectors, so you can later vectorize things:

index=randi([100,499],1,N_m);
x1_samp0 = x1(index);
x1_samp1 = x1(index+1);
...
Xdot1=(x1_samp1-x1_samp0)/dt;
...
M(:,1)=1;
M(:,2)=x1_samp0;
...
M(:,6)=x1_samp0.^2;

edit: changed my mind on other option; don't do it. Here are some general tips, though:

if you have a set of conditions that can be expressed as variable=first, variable=second, etc. -- use a switch instead of if-elseif
If you have a loop running over a set of conditions and operations which have nothing else in common -- just run each line individually, then fill in the "else" portion after

for j=1:N_basis
    if j==1
       M(i,j)=1;
    elseif j==2
       M(i,j)=x1(index(i));
    elseif j==3
       M(i,j)=y1(index(i));
    end
end

does the same as the below, but cleaner and faster:

M(i,1)=1;
M(i,2)=x1(index(i));
M(i,3)=y1(index(i));

many, many, many for loops can be replaced with vector operations. It's kinda the point of Matlab

Best Answer

Related Solutions

MATLAB: Preallocate an matrix in 2 for loops

MATLAB: How to take 100 samples of a plot.

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