Why this gives error?

LB=[0 0 0 0];
UB=[10 10 pi pi];
particles_x(1,1)=LB+rand*(UB-LB)

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

[Jan]

I've added the error message. Please care for including the message in future questions about errors.

Answer 1

[Jan]

LB = [0 0 0 0];
UB = [10 10 pi pi];
size(LB + rand * (UB - LB))

ans = 1×2

1 4

You cannot assign a [1 x 4] vector to the scalar particles_x(1,1).

Answer 2

[KuriGohan]

You get a 1x4 array on the right that you want to save inside the first row of the first column of the array - you cant do that. Just write particles_x=LB+rand*(UB-LB) and then particles_x(1,1) to acess what you want (at least what i think you want, that is the first element of that matrix).

[Sadiq Akbar]

Thanks to both of you Jan and KuriGohan for your prompt response. But actually, This is inside an algorithm and when I change it like this:

LB=[0 0 0 0];
UB=[10 10 pi pi];
particles_x(1,:)=LB+rand*(UB-LB)

Then it doesn't give error but then I get -ve answers also. So what to do so that I don't get -ve answers?

[KuriGohan]

Acess just what you want - in your case:

LB=[0 0 0 0];

UB=[10 10 pi pi];

particles_x(1,:)=LB+rand*(UB-LB);

particles_x = particles_x(1,1)

[Sadiq Akbar]

Thank you very much dear KuriGohan for your prompt response.Actually the code of the algorithm is at: https://www.mathworks.com/matlabcentral/fileexchange/67768-a-hybrid-firefly-and-particle-swarm-optimization-hfpso?s_tid=FX_rc2_behav

If you download it, it works for scalar bounds but gives an error of dimension mismatch. So when I do changes as mentioned above, then i get -ve values in results also which is not required.

[Jan]

What are "-ve values" ?

[Voss]

I gather "-ve" means "negative" (so the "-" stands for "negati", I guess).