Subscript indices must either be real positive integers or logicals.

I am doing a work for my class and in this equation:

p(f)=(((sum(sin(2*pi*f*(ti-t)))).^2)/(sum(sin(2*pi*f*(ti-t)).^2)))+((sum(cos(2*pi*f*(ti-t)))).^2)/(sum(cos(2*pi*f*(ti-t).^2)));

it gives me this error :

Subscript indices must either be real positive integers or logicals.

ftab3 is a matrix 82x2; ti is a vector 1:20

and previoulsy i did a for

tab3=[zred d18Ored];

for f=1:0.2:20;

     ftab3=tab3*f;

     for ti=1:20

       t=(1./(4*ftab3*pi))*atan(sum(sin(4*ti*ftab3*pi))/(sum(cos(4*pi*ftab3*ti))));

       p(f)=(((sum(sin(2*pi*f*(ti-t)))).^2)/(sum(sin(2*pi*f*(ti-t)).^2)))+((sum(cos(2*pi*f*(ti-t)))).^2)/(sum(cos(2*pi*f*(ti-t).^2)));

     end

end

any help would be gratful! thanks

Answer 1

[Thorsten]

for f=1:0.2:20; and in the loop p(f) = , so you try to eval p(0.2) = ... which is not allowed. f=0.2 is used as a subscript index, but Matlab allows only positive integers as subscripts, like f(1), f(2), and so on.

You can use

flist=1:0.2:20;
for i = 1:numel(flist);
   f = flist(i);
   % other code
   p(i) =  
   % other code
end