The following transfer function has zero/pole cancelation. I am trying to create a transfer function object, but Maple automatically simplifies the transfer function before it gets to the DynamicSystem call, which result in different output than what I expected.

I do set the cancellation=false option, even though this is the default. The problem is Maple does pole/zero cancelation before the call.

I tried to add '' around it to delay evaluation, but it did not work.  

restart;
alias(DS=DynamicSystems):
DS:-SystemOptions(cancellation=false,complexfreqvar=s):
tf:=DS:-TransferFunction('-(s - 1)/((-2 + s)*(s - 1))'):
DS:-PrintSystem(tf)

You can see it did pole/zero cancelation.

In Matlab and Mathematica, this does not happen. For example

Clear["Global`*"];
sys = TransferFunctionModel[-(s - 1)/((-2 + s) (s - 1)), s]

Same with Matlab:

>> s=tf('s');
>> sys_tf =-(s - 1)/((-2 + s)*(s - 1))

sys_tf =
 
     -s + 1
  -------------
  s^2 - 3 s + 2
 
Continuous-time transfer function.

What do I need to do in Maple to keep the transfer function without pole/zero cancelation (this affects the state space realization later on when this cancelation happens)

I am using Maple 2019 at this moment as Maple 2020 is busy.

As I was going over latest build using Physics:-Latex I noticed this.

The complex number I should be translated to lower case i  in latex.

This is what the original latex() does (and also what Mathematica TeXForm does).

It does not look good at all to have complex number I be translated to I and remain UPPER case I

Here is an example

expr:=[solve(x^2+2*x+2=0,x)];
Physics:-Latex(expr)

gives

[-1+I, -1-I]

While  latex(expr) gives the much better and more mathematical output:

[-1+i,-1-i]

Is it possible to have Physics:-Latex translate complex numbers like latex() did?

Please see attached worksheet below.

Download latex_issue_9.mw

I'd like to suggest Physics:-Latex change its use of \textit{} and replace it with \mathit{} 

\mathit is the better Latex command to use, since the Latex generated goes into math mode and \mathit is designed to be used in math mode and hence has a better spacing for this. Making the final Latex look a little better.

Here is an example showing the difference.

restart;
ode:=diff(y(x),x) = y(x)/(x^2+1);
sol:=dsolve(ode);
Physics:-Latex(sol)

Gives

y \left(x \right) = \textit{\_C1} {\rm e}^{\arctan \left(x \right)}

It will be better to generate

y \left(x \right) = \mathit{\_C1} {\rm e}^{\arctan \left(x \right)}

Here is the difference when both are compiled using latest texlive 

Since all the Latex generated is meant to be used in math mode, \mathit would be better choice. It is considered wrong to use \textit in math mode actually, even though it does compile.

Here is the latex file used to generate the above pdf

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{maplestd2e}


\begin{document}

\[
y \left(x \right) = \textit{\_C1} {\rm e}^{\arctan \left(x \right)}
\]

\[
y \left(x \right) = \mathit{\_C1} {\rm e}^{\arctan \left(x \right)}
\]

\end{document}

thank you

Download latex_issue_8.mw

I've been using Physics:-Latex in my large program, and checking the output visually. I noticed this small issue on one page.

When asking Physics:-Latex to generate Latex for this expression

It gives

While when using standard latex() command, the result is

Below is the worksheet attached. Using Latest Physics and Maple.
 

THe latex file used to compile the Maple output Latex using TeXLive distribution on Linux is

\documentclass[12pt]{article}
\usepackage{amsmath}
%\usepackage{maplestd2e} %not needed for this example
\begin{document}

%output of Physics:-Latex()
\[
\frac{\left(\int {\rm e}^{-t} f \left(t \right)d t \right) {\rm e}^{t}}{2}+-\frac{1}{2} {\rm e}^{-t} \left(\int {\rm e}^{t} f \left(t \right)d t \right)
\]

%output of maple latex()
\[
{\frac {\int \!{{\rm e}^{-t}}f \left( t \right) \,{\rm d}t{{\rm e}^{t}}}{2}}-{\frac {{{\rm e}^{-t}}\int \!{{\rm e}^{t}}f \left( t \right) \,{\rm d}t}{2}}
\]

\end{document}

Download latex_issue_5.mw

I spend all day on this, since some tests I have were failing when I changed to using Physics:-Latex() vs. latex(). I made no change at all in my own code other than to replace latex() by Physics:-Latex().

I am still not sure why that is, but it seems due to symbol clash somewhere.  First time I run my test, it passes, next time if fails. When I change back to latex(), the test passes each time.  

This seems to be due to when calling Physics:-Latex() the very first time, it automatically changing diff(y(x),x) to y'(x). May be it is storing its own x in there. (this happens on special input and not for each input, that is why only some tests fail and not all of them).

So next time I call the test it failes. May be due to different x being used. I do not know. 

All what I know now is that using latex() makes my dsolve test passes each time.  

But here I will show the issue which I think if fixed, should fix the main problem.

Calling Physics:-Latex() causes it to automatically change diff(y(x),x) to y'(x)  even though I am not using Typeseeting at all. 

restart;
s:= y = u*x:  #special case input which causes the typesetting to kick in
ode:=diff(y(x),x)=1:
print(ode);
Physics:-Latex(s,output = string):
print(ode);

Notice how the derivative changes on its own to using y'(x).  Now compare with latex()

restart;
s:= y = u*x:
ode:=diff(y(x),x)=1:
print(ode);
latex(s,output = string):
print(ode);

So something happens inside Physics:-:Latex which causes this.  

For now, I will change back to latex() until I figure more what is going on so that my test do not fail. I like to use Physics:-:Latex as it made the latex look much better.

Maple 2020.1, Physics 778
 

Additional observation

This change of typesetting does not happen all the time. For example if s:= y = x: then it works OK. i.e. it does not change typesetting. But if s:= y = u*x: then it changes typesetting. which is very strange why that is.

I stepped into Physics:-Latex using the debugger., The typesetting changes after the call to Physics:-Latex:-Print.

Download latex_issue_2.mw