MATLAB: Basic Vector Operations

Question

Hello, I am currently familiarizing myself with MATLAB for my research. I was asked to create a program that reads in two vectors from the user and then graph them. I am currently having difficulty correctly performing the the addition and multiplication of these vectors. I am new to this website and MATLAB as a whole. I was hoping someone could assist me in any way.

Thank you, first and foremost for your support. I have spent the last couple of days researching operation techniques and I have come up with the following code for each different function (all of function data may not be included)

for addition:

    a = get(handles.textvector1,'String');
    b = get(handles.textvector2,'String');
    %if length is the same

    if length(a) == length(b)
    %add vectors    

    c = a + b;
    %set text to result

    set(handles.textvectorresult,'String',c);
    %plot result

    plot(c)
    % or display error message

    else
        errordlg('Please enter vectors of same size','Size mismatch error','modal')
    end
      and for multiplication:
a = get(handles.textvector1,'String');
b = get(handles.textvector2,'String');
%if length is the same
if length(a) == length(b)
%add vectors    
c = a .* b;
%set text to result
set(handles.textvectorresult,'String',c);
%plot result
plot(c)
% or display error message
else
    errordlg('Please enter vectors of same size','Size mismatch error','modal')
end
     I end up getting unusually high numbers

Thanks, Prince Njoku

Answer 1

Matrices and Arrays

• Multiplication (note the dimensions):

 (1:10)   * (21:30).' = scalar  % 1 by 10 times 10 by 1 - inner/dot product
 (1:10).' * (21:30)   = matrix  % 10 by 1 times 1 by 10 - outer product
 (1:10)  .* (21:30)   = vector  % elementwise multiplication

.

• Summation (again note the dimensions)

(1:10)  + 10 or rand(2) + 10 % vector/matrix plus scalar
(1:10)  + (11:20)            % same dim vector addition
rand(2) +  ones(2)           % same dim matrix addition

EDIT

You're retrieving text and doing operations on strings not numbers. To see what I mean try this:

'65' .* '33' 
 65   *  33

To convert strings to numbers a wrapper is:

str2double('65')

or manually for positive numbers:

tmp  = '65' - '0';
nTmp = numel(tmp);
out  = tmp*(10.^(nTmp-1:-1:0)).';