SMath was very recommended in the FreeCAD and Blender forums, so then IMHO should exist an integration between SMATH and FreeCAD/Blender

Feel free to create the plugin . SMath has not even reached an official REV. 1
I believe this is what you are looking for
* MathCAD 8.0 Pro Student Edition contained: - drawing program (from Intergraph) which allowed for import of drawings whose dimension variables could be part of the MathCAD worksheets
* There were add-ons for MathCAD 14/15 and AutoCAD (Plugin Retired this year PTC MathCAD Downloads
* Prime has integration with CREO (same company). I'm not sure if they still integrate with AutoDesk as they are a competitor.

I am interested more in SMath, I could try to create a Python plung-in for an integration between FreeCAD and Blender with SMath, but how? is there any book for use Smath with Python?

Wrote

I am interested more in SMath, I could try to create a Python plung-in for an integration between FreeCAD and Blender with SMath, but how? is there any book for use Smath with Python?

Andrey, Davide, Martin, and Uni are likely your best sources. You will want to look at SMath Extensions. Specifically, How to create plugins for SMath Studio. I'm a user, not a developer. Sorry I cannot help anymore

Wrote

Feel free to create the plugin . SMath has not even reached an official REV. 1
I believe this is what you are looking for
* MathCAD 8.0 Pro Student Edition contained: - drawing program (from Intergraph) which allowed for import of drawings whose dimension variables could be part of the MathCAD worksheets
* There were add-ons for MathCAD 14/15 and AutoCAD (Plugin Retired this year PTC MathCAD Downloads
* Prime has integration with CREO (same company). I'm not sure if they still integrate with AutoDesk as they are a competitor.

I'd go for Matlab and Solidworks integration. Though i do not know of any free form design sw (3DS Max, Maya, Cinema4D, Rhinoceros or even Blender) to have integration with CAS/numerical analysis software.

Regarding Blender, i'd say the way to go is Blender<->Python<->ScyPy<->??

python is powerful but I wish to have a library in Smath and use it in Blender together maybe with Sverchok Node Editor, because Smath has a beautiful paper-system-latex and is too comfortable, being blender and FreeCAD open-source, could be a good idea to create an integration between both.

but sadly look like devs do not use Blender and FreeCAD, I hope a day we can use a Smath 1.0 and open-source with integration with others open-source.

Wrote

python is powerful but I wish to have a library in Smath and use it in Blender together maybe with Sverchok Node Editor, because Smath has a beautiful paper-system-latex and is too comfortable, being blender and FreeCAD open-source, could be a good idea to create an integration between both.

but sadly look like devs do not use Blender and FreeCAD, I hope a day we can use a Smath 1.0 and open-source with integration with others open-source.

Creo que hablamos el mismo lenguaje...

I guess you're mostly interested in maths and geometry, and not thinking of how to model physics in CAD systems. And you appreciate the beauty in the results. There are several approaches to integrate CAD sw with a program like Smath, so: where do you really want to get to?
- I suggested Matlab + Solidworks for I was thinking of physical systems modeling (Edit: but you could try OpenModelica).
- I mentioned other surface modelling tools, because Blender is a surface modeling tool(and i prefer Sketchup or Solidworks to FreeCad). If you want to do maths with Blender, using Python + NumPy / SciPy / ... might be a good approach. If you just want to manipulate geometry, Sverchok might be enough.
- And finally, if you want to create beautiful paper-like documents, including 3d model visualization... I'd go for HTML. You can export Smath documents to HTML and embed 3D (VRML, ...) in HTML too.

Espero haber ayudado.

Wrote

so: where do you really want to get to?

The real question

"Integrate“ has a very wide meaning... do you want to display models, preprocess/postprocess data files, manipulate stuff in real time (a front-end interface?), ...?