Is there any way to get numerical result from symbolic function?

Hi,

I have a smybolic function created by syms command and at the next steps in my code, i should get numerical output by using this function. To do this operation, i copy the symbolic function from workspace and paste my editor. This is too long method and easy to make mistake. So, i have to use symbolic function directly.

What kind of methods can i use for this operation? Do you have any example about this?

Thx!

Answer 1

[Ameer Hamza]

If you have a symbolic function, you can directly evaluate by giving the input. For example

syms x
y(x) = x.^2 + 2*x + 3; % symbolic function

Then run the following

>> y(3)
ans =
18
>> y(100)
ans =
10203

If you want output in floating-point format, you can use double()

double(y(100))

If you have a symbolic expression, then you can use subs()

syms x
y = x.^2 + 2*x + 3; % symbolic expression

and then run

>> subs(y, x, 3)
ans =
18
>> subs(y, x, 100)
ans =
10203

Answer 2

[KSSV]

You can substitute a variable value in the syms using subs and then use double, vpasolve to convert into numerica array.

Read about subs, double.

Answer 3

[Walter Roberson]

Use matlabFunction to convert the expression into a numeric function.