Hi...can we create a variable "a" with double array type ? . Thank.

i did tried commands : str2num,str2double...but it not true

[Jan]

The question seems to be clear, but in the discussion we see, that you want something else. It seems like you have confused numeric and symbolic variables. So please edit the question and add more details of what you want to achieve.

[super bad]

thank bro.. I am from Vietnam, my English is not good.

[Jan]

Your English is fine enough to explain the problem with more details. I'm not a native English speaker also, like many other users of this forum. Beside the language, it is difficult to explain a problem in general, because as long as it is not solved, it is not clear, which parts are relevant or not. Simply try to explain it again with more details. Prefer to edit the question, such that the reader find all details in one location.

I'm not "bro", but I have a name: "Jan". I assume, the other persons in the forum not "bros" also. ;-)

Answer 1

[Adam]

a = 7;

is a variable 'a' of type double.

Or even

a = [];

is also type double, but with empty contents.

[super bad]

No bro It is not so easy. I want to create a matrix has value is 'a'. 'a' function is like a number and in the form of double array in class...can we do it?

Answer 2

[John D'Errico]

You want to create an array that has double precision class, thus a "double", but contains a string, 'a'.

Sorry, but you cannot do so. A double can contain ONLY numbers. Those elements must all be of class double.

If you create an array that contains a string, 'a', it must be either of class char, or a cell array.

A = 'a'
A =
    'a'

B = {'a'}
B =
  1×1 cell array
    {'a'}

whos
  Name      Size            Bytes  Class    Attributes

    A         1x1                 2  char               
    B         1x1               114  cell

[Guillaume]

it must be either of class char, or a cell array

or, as of R2016b, a string:

 C = string('a');  %R2016b
 C = "a";          %R2017a or later

[super bad]

thank bro. And you know how to create a tranfer function like this?

s + a
--------
s + b
without using the command ( pretty).

[Jan]

I depends: How do you want to use this function? Please explain more details.

[super bad]

s + a

--------

s + b

it is a transfer function , we can ( +, -, * / ) it with other tranfer function. i think we can't do it. But it is my test.

[Image Analyst]

Try this:

function result = MyTransferFunctions, a, b)
result = (s+a)./(s+b)

You pass in s, a, and b of course. If that's not right, then let's finally get an explanation that is clear, preferably with some numerical examples.

[super bad]

a,b is the coefficient in front of s , if (a or b) is a string or symbol then we were wrong

[Jan]

@super bad: This sound really magic. I still do not have any idea, what you are talking about. What is "a", "b" and "s"? What are your inputs, what is the wanted output and which problem do you try to solve? Why do you want to operate on "strings", "symbols" (what ever this is) and numerical matrices at the same time?

Answer 3

[Mridul Gandhi]

Maybe you mean this:

I=5;
J=5;
a=sym('a',[I J]);

Creates variable 'a' of size (IxJ):

a =
 
[ a1_1, a1_2, a1_3, a1_4, a1_5]
[ a2_1, a2_2, a2_3, a2_4, a2_5]
[ a3_1, a3_2, a3_3, a3_4, a3_5]
[ a4_1, a4_2, a4_3, a4_4, a4_5]
[ a5_1, a5_2, a5_3, a5_4, a5_5]

[Thong Phan]

Yes but each a1_i is not double type

[Rik]

As detailed in several comments: that is not possible. There are many options of what you could mean in this thread. Which do you want?