multipying character in array number

i want to create a character array for example if a.*[1 1 1 1] we get [a a a a] thank you.

Answer 1

[Azzi Abdelmalek]

repmat({'a'} ,1,5)

[best16 programmer]

thank you. but what if we have a.*[1 -1 1 -1 -1] how can we get [a -a a -a -a]

Answer 2

[Star Strider]

‘what if we have a.*[1 -1 1 -1 -1] how can we get [a -a a -a -a]’

That requires a loop, but it works:

v = [1 -1 1 -1 -1];
a_vec = [];
for k1 = 1:length(v)
    if v(k1) > 0 
        a_vec = [a_vec ' a '];
    elseif v(k1) < 0
        a_vec = [a_vec '-a '];
    elseif v(k1 == 0)
        a_vec = [a_vec ' 0 '];
    end
end

a_vec =
 a -a  a -a -a

[best16 programmer]

thank you ,it works.how we can generate the vector v in a random way.

[Star Strider]

My pleasure.

Note that it also allows for ‘0’ entries in ‘v’.

[James Tursa]

To generate a random vector with the values either +1 or -1, see this link:

http://www.mathworks.com/matlabcentral/answers/306783-a-matlab-code-of-getting-a-value-uniformly-at-random-from-a-the-set-1-1

Answer 3

[Philip Borghesani]

Did you really want a character array?

 >> syms a
 >> b=a.*[1 -1 1 -1 -1] 
  b =
  [ a, -a, a, -a, -a]

To get a character array you can do

 >> char(b)
 ans =
    'matrix([[a, -a, a, -a, -a]])'