Index exceeds the number of array elements (1).

t1=-1:0.1:0.5;
t2=0.6:0.1:3;
t= [t1 t2];
x1=0.6.*ones(size(t1));
x2=0.3.*ones(size(t2));
x=[x1 x2];
h=(exp(-t)).*(t>=0);
C=length(x)+length(h)-1;
X=0;
H=0;

for i=1: C
c(i) = 0;
for j=1:i
if(i-j+1>0)
c(i)= c(i)+ X(j).* H(i-j+1);
else
end
end
end
plot(c)

I'm trying to v=convolve x and h but everytime i run this it gives me the array size error.

I'm using MATLAB Online R2020a, and when I gave this code to someone who had RMATLAB2015a installed on their computer, there was no error.

error is in line 16:

c(i)= c(i)+ X(j).* H(i-j+1);

[KSSV]

What is that code? It is full of mess. What exactly you are trying?

Answer 1

[Ayush Goyal]

From my understanding of the question you are trying to find the convolution of x and h but you are facing array size error. Error is due to different length of vectors x and h and you should transform the vectors x and h in new vectors X and H with the same length. Change the code for X and H and instead of iterating j from 1 to i iterate it from 1 to length(x)

t1=-1:0.1:0.5;
t2=0.6:0.1:3;
t= [t1 t2];
x1=0.6.*ones(size(t1));
x2=0.3.*ones(size(t2));
x=[x1 x2];
h=(exp(-t)).*(t>=0);
C=length(x)+length(h)-1;

X=[x,zeros(1,length(h))]; %zeropadding to have vectors of equal length
H=[h,zeros(1,length(x))]; %zeropadding to have vectors of equal length
for i=1: C
c(i) = 0;
for j=1:length(x) %Iterate it from 1 to length(x)
if(i-j+1>0)
c(i)= c(i)+ X(j).* H(i-j+1);
else
end
end
end
plot(c)

You can refer to the following link:

https://www.mathworks.com/matlabcentral/fileexchange/23402-convolution-in-matlab-without-using-conv-x-h

[Sam Frank]

Thankyou! I'm still new to MATLAB and doing convolution no less. I didn't even know what zeropadding was :p. Thanks for helping out.