Sum function discrite time

hello guys, i am beginner, i try to solve this however just did this equation and no more y3 = symsum(x,k,1000,6000);

Thank for your support

[Walter Roberson]

In practice, you cannot use symsum() for recursive formulas: if x[n] is defined in terms of x[previous value] then you will need to define the output through iteration. symsum() is only for cases where you can define each individual element according to a formula that can be computed without computing the previous entries.

Also, you can never use a symbolic variable as a subscript, so you cannot use symsum() with subscripting. It is not for example possible to do

X = randi(9, 1, 10);
syms n
symsum(gamma(X(n)), n, 1, 10)    %NOT LEGAL

Instead you should take the different definite values and sum them:

sum(gamma(X))

Answer 1

[Mathieu NOE]

hello

this is an example of echo simulation - please adapt to your parameters

hope it helps

clear all;
close all;
infile='DirectGuitar.wav';
outfile='out_echo.wav';
% read the sample waveform
[x,Fs] = audioread(infile);

% normalize x to +/- 1 amplitude
x = x ./ (max(abs(x)));

% parameters 
N_delay=20; % delay in samples
C = 0.7; % amplitude of direct sound

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

y = zeros(length(x),1);       % create empty out vector
y(1:N_delay)=x(1:N_delay); % to avoid referencing of negative samples

% for each sample > N_delay
for i = (N_delay+1):length(x)
    y(i) = C*x(i) + (1-C)*(x(i-N_delay));   % add delayed sample
    
end

% write output
% normalize y to +/- 1 amplitude
y = y ./ (max(abs(y)));
audiowrite(outfile, y, Fs);

figure(1)
hold on
plot(x,'r');
plot(y,'b');
title('Echoed and original Signal');
sound(y,Fs);