What's the difference between sin(t) and square(t)?

If I code like

signal1 = sin(t);

signal1 = square(t);

then

The first one is valid but the second one is invalid showing 'Input arguments must be 'double'.'

It looks like same as built-in functions but the usages is different

What's the difference between those as the usages??

Answer 1

[John D'Errico]

Let me guess. You have defined t to be a symbolic variable?

You can verify that using the whos command. Thus, if I do this:

syms t
whos t
  Name      Size            Bytes  Class    Attribute
  t         1x1                 8  sym                

So t is symbolic, as you see above.

I can use sin(t), because the symbolic toolbox can work with the sin function. However, square is a function from the signal processing toolbox. It REQUIRES double precision inputs. Therefore, you get an error message.

Not all functions are defined for symbolic input.

[Kyungsik Shin]

Thanks a lot

It was the matter of declaration of the functions!