# Convolution, discrete time (not using conv)

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umar on 17 Dec 2011
Answered: sahiba tasneem on 24 Jul 2017
Write a MATLAB routine that generally computes the discrete convolution between two discrete signals in time-domain. (Do not use the standard MATLAB “conv” function.) • Apply your routine to compute the convolution rect( t / 4 )*rect( 2 t / 3 ).

umar on 18 Dec 2011
If i use below coding, how to put rect(t/4) and rect(2t/3)in x and h? Please can anyone answer this?
% A GENERALAZED CONVOLUTION COMPUTING CODE IN MATLAB WITHOUT USING MATLAB BUILTIN FUNCTION conv(x,h)
close all
clear all
x=input('Enter x: ')
h=input('Enter h: ')
m=length(x);
n=length(h);
X=[x,zeros(1,n)];
H=[h,zeros(1,m)];
for i=1:n+m-1
Y(i)=0;
for j=1:m
if(i-j+1>0)
Y(i)=Y(i)+X(j)*H(i-j+1);
else
end
end
end
Y
stem(Y);
ylabel('Y[n]');
xlabel('----->n');
title('Convolution of Two Signals without conv function');
Friðrik Hover on 21 Feb 2016
Running this code and and also the built in conv function to convolute two signals makes the x axis wrong. How do you fix that?

Naz on 17 Dec 2011
just implement the equation http://en.wikipedia.org/wiki/Convolution#Circular_discrete_convolution and use sum from 1 to N instead of 0 to N-1

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Wayne King on 17 Dec 2011
I think Naz has given you some direction here, but you have just posted your homework problem. If you show what you have coded in trying to solve your homework problem, people are generally more helpful.
umar on 17 Dec 2011
to be honest. We are taking signal course. We do not learn about MATLAB in this course. Actually, i do not have any idea how to start.
yuki kim on 2 Apr 2017
me too...