Error using / Invalid operands

Problem:

I'd like to calculate a limit, but for some reason I can't use the '/' operand. Can somebody explain why?

Error message:

Error using / (line 485)

Invalid operands.

Code:

syms s;
limit(s/(((2*eulergamma^(-23*s)/a)*1.07 + 0.0114/s + 25.3045*s))*1/s, s, 0)

[Ive J]

I assume a is a vector(?)

what about this?

limit(s./(((2*eulergamma^(-23.*s)./a)*1.07 + 0.0114./s + 25.3045.*s))*1./s, s, 0)

[Damián Bombara]

That worked but I've changed it up a bit and I got new error message :D

GS is a transfer function and GRS is holding 3 things, P, I & D parameters of PID regulator

limit((s.*1./s)./(1 + GS*GRS), s, 0)
Error using sym/subsindex (line 953)
Invalid indexing or function definition. Indexing must follow MATLAB indexing. Function arguments must be symbolic variables, and
function body must be sym expression.

Error in sym/subsref (line 997)
            R_tilde = builtin('subsref',L_tilde,Idx);

[Ive J]

Maybe you can share GS and GRS? I guess something's wrong with GS definition (have you seen here?).

[Damián Bombara]

GRS: val =

(50609*s)/2000 + 57/(5000*s) + 107/100

GS: val =

(2/eulergamma^(23*s))/((93*s)/2 + 1)^2

[Ive J]

I can't replicate the error:

syms s;
GRS = (50609*s)/2000 + 57/(5000*s) + 107/100;
GS = (2/eulergamma^(23*s))/((93*s)/2 + 1)^2;

limit((s.*1./s)./(1 + GS*GRS), s, 0)

ans = 

0

BTW, you should note that there is a huge difference between * and .* in MATLAB

https://se.mathworks.com/help/matlab/ref/times.html

https://se.mathworks.com/help/matlab/ref/mtimes.html

[Damián Bombara]

That's weird, now it's working. I didn't change anything but it works.

Well, thank you very much for your help, I really appreciate it!

Answer 1

[Damián Bombara]

@Ive J solved it in the comments.