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Concatinating signals on Matlab

  1. Jan 31, 2013 #1
    Hiiiiii Everyone ,

    It is My First Post ....And I will be Very pleased if You helped me find a solution to my problem .

    well... It is a Matlab code &

    I have different type of signals (impulse ,Ramp, sinusoidal,Dc ,exponintial )

    & the type of signal is determined by the user ( the user enter a number from 1 to 5) to determine the signal & the user can have multiple selection ..& the user tells me how many time he want to select signals

    But The Problem i don't Know how to concatenate the signal .. I tried to make it like this
    for i=1:c+1
    A=[A y(choice)]
    but an error keeps bothering me
    ??? In an assignment A(I) = B, the number of elements in B and
    I must be the same.

    please any one help me..
  2. jcsd
  3. Jan 31, 2013 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    So if you are storing the possible signals in vectors m1 m2 etc, and the user constructed vector is a, then, at each selection, you are doing a=[a,m1] (if type 1 was selected).
    I think your error means that you have made a mistake in your assignments to do with the vector size. Check that you are concatenating to the right place with the correct orientation.

    But I suspect it is the y(choice) part ... matlab would see that as an assignment of form A(I)=B you see?

    Code (Text):

    7> m=magic(4)
    m =

       16    2    3   13
        5   11   10    8
        9    7    6   12
        4   14   15    1

    8> a=m(1,:)
    a =

       16    2    3   13

    9> a=[a,m(4,:)]
    a =

       16    2    3   13    4   14   15    1

    10> a=[a,m(:,3)]
    error: number of rows must match (4 != 1) near line 10, column 6

    10> a=[a;m(3,:)]
    error: number of columns must match (4 != 8)
    To be able to tell what is going wrong for you I need to see the code and the context for the error (the actual error message copy-and-past).
  4. Feb 1, 2013 #3
    Thanks Monsieur simone For Your Help :)

    But That wasnot the point that i was asking about .. You R Right you have to see the code to be able to see the problem

    c=input('enter the number of break point: ');

    for n=1:c
    m(1,k)=input('enter positions of break point:');
    p=[-5 m 3]; % The signal start at -5 & end at 3 & m is the position of the break

    for k = 1:c+1
    t=linspace(p(1,k),p(1,k+1),(p(1,k+1)-p(1,k))*100); % the frequency =100
    choice=menu('Choose a type','y(1)','y(2)','y(3)','y(4)','y(5)');
    if choice==1
    y(1)=[4 zeros(1,(g-1))];
    if choice==2
    if choice==3
    if choice==4
    if choice==5

    % Here i want to conatenate all the choosen signals & Plot it With T
    % But i can't Write the proper code of concatination


  5. Feb 1, 2013 #4

    Simon Bridge

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    Science Advisor
    Homework Helper

    I can see a number of problems with the below:

    c=input('enter the number of break point: ');

    for n=1:c
    m(1,k)=input('enter positions of break point:');
    ... you have not defined k - change the n to a k or the k to an n.

    With this change, the output looks like this:
    Code (Text):
    48> sig
    enter the number of break point: 3
    enter positions of break point:0.1
    enter positions of break point:0.2
    enter positions of break point:2
    Choose a type

      [ 1] y(1)
      [ 2] y(2)
      [ 3] y(3)
      [ 4] y(4)
      [ 5] y(5)

    pick a number, any number: 1
    error: A(I) = X: X must have the same size as I
    error: called from:
    error:   /home/simon/sig.m at line 15, column 5
    line 15 is:
    if choice==1
    y(1)=[4 zeros(1,(g-1))];

    consider: what does "y(1)" mean to matlab?

    - what do you y to look like?
    if you want y to be a row vector containing the signal, then you can build it as you go.
    something like:

    y=[y,[4 zeros(1,(g-1))] ];

    That gets rid of the error but there are other problems.

    Work through your loops by hand - pick c=1 and choose 0 so that p=[-5,0,3] and see what happens. Make sure it's what you want to happen.
    What happens if the user chooses break point positions out of order? i.e. if c=2, and the first point is 2 and the second is -1?
    What happens if the user chooses non-integer break point positions?
    I'm guessing you'll work out how to build a horizontal axis later?


    [*] Shouldn't that be by Monsieur (Simon) Dupont for French? IIRC: "Simone" is the feminine spelling in French as it is in English so you are kinda implying that you think I'm a girl? Mind you - if I'm an honorary woman then I get to be "right" don't I so... no complaints there ;)

    It is masculine in Italian though - for "Signor (Simone) Ponte" or something(?)
    Last edited: Feb 1, 2013
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