i am a newb on matlab. why i've got some error with this. please help me

clear all; clc
[x,s] = xlsread("nilaifreq.csv");
freq_list = freq_list >= 0.04 & freq_list < 0.15;

% sum all power value with freq. range from LF  criteria
lf_data = pow_list(freq_list >= 0.04 & freq_list < 0.15);
sum_lf_data = sum(lf_data);
C = [C char(10) 'sum all power value with freq, range from 0.04 to 0.15 for LF criteria...'];

% sum all power value with freq. range from HF criteria
hf_data = pow_list(freq_list >= 0.15 & freq_list <= 0.4);
sum_hf_data = sum(hf_data);
C = [C char(10) 'sum all power value with freq, range from 0.15 to 0.4 for LF criteria...'];

% ratio LF/HF
ratio_lf_hf = sum_lf_data / sum_hf_data;
C = [C char(10) 'ratio LF/HF...'];

please help me, i want to sum the data power just include in frequency 0.04 to 0.15. i write the code, but got error.

[DGM]

You'll have to mention what error you're actually getting.

% placeholder data
freq_list = rand(10,1)/2;
pow_list = (1:10).';
C = [];

% all this does is convert freq_list to a logical vector
% which breaks everything
%freq_list = freq_list >= 0.04 & freq_list < 0.15;  % don't need this

% sum all power value with freq. range from LF  criteria
lf_data = pow_list(freq_list >= 0.04 & freq_list < 0.15);
sum_lf_data = sum(lf_data);
C = [C char(10) 'sum all power value with freq, range from 0.04 to 0.15 for LF criteria...'];

% sum all power value with freq. range from HF criteria
hf_data = pow_list(freq_list >= 0.15 & freq_list <= 0.4);
sum_hf_data = sum(hf_data);
C = [C char(10) 'sum all power value with freq, range from 0.15 to 0.4 for HF criteria...'];

% ratio LF/HF
ratio_lf_hf = sum_lf_data / sum_hf_data;
C = [C char(10) 'ratio LF/HF...'];

Idk if there's some problem with how the file is imported or something, but this runs.

[Cris LaPierre]

Use the paperclip icon to attach your csv file to your post.