Subtraction of Two sequences

Hello everyone ,

I am very new to this programming language ,I have started writing simple programs and encountered following errors 
1. Input argument "n1" is undefined.

*Error in ==> subseq1 at 6 n=(min(min(n1),min(n2)): max(max(n1),max(n2))); * And yet if I try to give the ouptut as the foll. subseq1(-3:3,[3 :2 :15],0 :4,2:6)

and command window displays all the variables with assigned values ..and shows the signal sub. But My query is Can I debug the error? if So How? Below is the code for reference :

{
%x1=first sequence of range n1
%x2=second sequence of range n2

function[y1,y2,a,b]= subseq1(n1, x1, n2,x2) clc; n=(min(min(n1),min(n2)): max(max(n1),max(n2)));

y1=zeros(1,length(n)) y2=y1 a=(n>=min(n1))&(n<=max(n1)) b=(n>=min(n2))&(n<=max(n2)) y1(a)=x1 y2(b)=x2 y=y1-y2 subplot(3,1,1) stem(n1,x1) title('sequence x1') xlabel('n1------------' ) ylabel('x1------------ ') subplot(3,1,2) stem(n2,x2) title('sequence x2') xlabel('n2------------ >') ylabel('x2------------ >') subplot(3,1,3) stem(n,y) title('subtraction of 2 sequence' ) xlabel('n------------ >') ylabel('y------------ >')

Please help me !

[TAB]

Please format your code to make it readable.

[Sk Group]

For answer please click the link below to view the complete article. Subtraction of Sequences in MATLAB

Answer 1

[Wayne King]

Hi, please format your code for readability in future posts.

Save the function subseq1.m in a folder on the MATLAB path and then call it at the command line as:

[y1,y2,a,b] = subseq1(-3:3,[3 :2 :15],0 :4,2:6);

Here is your function:

function[y1,y2,a,b]= subseq1(n1, x1, n2,x2) 
n=(min(min(n1),min(n2)): max(max(n1),max(n2)));
y1=zeros(1,length(n));
y2=y1;
a=(n>=min(n1))&(n<=max(n1));
b=(n>=min(n2))&(n<=max(n2));
y1(a)=x1;
y2(b)=x2;
y=y1-y2;
subplot(3,1,1)
stem(n1,x1);
title('sequence x1');
xlabel('n1------------' ); ylabel('x1------------ ');
subplot(3,1,2);
stem(n2,x2);
title('sequence x2');
xlabel('n2------------ >'); ylabel('x2------------ >');
subplot(3,1,3);
stem(n,y);
title('subtraction of 2 sequence' );
xlabel('n------------ >');
ylabel('y------------ >');

[Parul]

Thanks for your help!I did the necessary changes

Still its showing the same error ,"n1 undefined"

[Wayne King]

Then you're doing something wrong, because the above works perfectly for me. You're probably still calling your old subseq1.m.

Do this:

1.) Delete your old subseq1.m

2.) Copy and paste what I have given you into a new subseq1.m file and save that file in a folder, let's call it c:\mfiles

3.) in the MATLAB command window, >>cd c:\mfiles

4.) Enter >>pwd to make sure you are in that directory

5.) Enter

>> [y1,y2,a,b] = subseq1(-3:3,[3 :2 :15],0 :4,2:6);

Answer 2

[Sk Group]

Signal Subtraction function in MATLAB

MATLAB CODE:

function [g n] = sigsubtract(x1,n1,x2,n2)

if n1(1)< n2(1)

a = n1(1)

x1 = [zeros(1,abs(n1(1)-n2(1))) x1]

else

a = n2(1)

x1 = [zeros(1,abs(n1(1)-n2(1))) x1]

end

if n1(end)>n2(end)

b = n1(end)

x2 = [x2 zeros(1,abs(n1(end)-n2(end)))]

else

b = n2(end)

x2 = [x2 zeros(1,abs(n1(end)-n2(end)))]

end

n = a:b;

g = x1-x2;