how to overcome the error

Bmax=2000000; %maximum available bandwidth for OFDMA
noise=1e-9; %fixed noise power is assumed
p_fix=0.01; %fixed transmit power is assumed
N_UE=[10 20 30 40 50 ];
N_SC=[60 70 80 90 100];
for it=1:2
for t= 1:length(N_UE)
for r = 1:length(N_SC) 
throughput_E(t) = @(t)  Bmax * log2(1 + p_fix(t)*gamma(t) / sum(p_fix(1:t-1) .* gamma(t) ));
overall_throughput_E(t) = sum(sum(throughput_E(t)));
output_E(t,r)=overall_throughput_E(t);
output_E(t)_it(t,r,it)=output_E(t,r);
end
end
end.

If i run the code i am getting

Error: File: Line: 12 Column: 12
The input character is not valid in MATLAB
statements or expressions.

Answer 1

[KSSV]

This line is not correct:

output_E(t)_it(t,r,it)=output_E(t,r);

You should change it to:

output_Et_it(t,r,it)=output_E(t,r);

[Prabha Kumaresan]

After changing into

 output_Et_it(t,r,it)=output_E(t,r);

I am getting

Undefined function 'sum' for input arguments of type
'function_handle'.
Error in  (line 13)
overall_throughput_Et = sum(sum(throughput_Et));

[Walter Roberson]

It is not clear why you changed that code from your previous

overall_throughput_E(t) = sum(sum(throughput_E(t)));

Function handles can be:

1) Assigned to a variable, as in

MyFun = @(t) exp(-t) - sin(t);
SecondVariable = MyFun;

2) Passed to another function, as in

MyFun = @(t) exp(-t) - sin(t);
fzeros(MyFun, 5)

3) Invoked, as in

   sum(MyFun(0:.1:5))

Any other use is not valid. You cannot sum() a function handle, for example: you have to sum() the result of invoking the function handle.

[Prabha Kumaresan]

The reason i have changed the code is due to the throughput expression which was given below.

If i run the code i am getting the error as stated before.

throughput_Et = @(t)Bmax * log2(1 + p_fix(t)*gamma(t)/sum(p_fix(1:t-1).* gamma(t)));
  overall_throughput_Et = sum(sum(throughput_Et));
  output_E(t,r)=overall_throughput_Et;
  output_Et_it(t,r,it)=output_E(t,r);

[Walter Roberson]

You define

 p_fix=0.01; %fixed transmit power is assumed

which makes p_fix a scalar. But you are using p_fix(t) and p_fix(1:t-1) which assume that t is either empty or is exactly 1 or is true or false (otherwise you would be indexing outside the array.)

You are looping over it and t and r but your calculations do not use it or r so taking a 2D sum does not make any sense.

Answer 2

[Walter Roberson]

Your code line is

    output_E(t)_it(t,r,it)=output_E(t,r);

Underscore is not a valid character immediately after the (t)

[Prabha Kumaresan]

ok