Show calculation formula for driven dimension

[an.niki]

Hi Everyone!

Fusion does have a mathematics library or integrator or solver (i don't know the right term for it) running in the background to calculate driven dimensions.

Is there a possibility to show the formula which is used to calculate the driven dimensions?

I sometimes have complicated geometrical problems which i can sketch with constraints and see the results with driven dimensions.

I would like to be able to follow the mathematical steps to get to the results.

Kind Regards,

Niklas

 

[Marco.Takx · Accepted solution]

Hi @an.niki,

There is no math behind it.

It generates a driven dimension if the geometry is already fully defined by other dimensions or constraints.

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[an.niki]

Hi @Marco.Takx 

There is also the possibility to add a dimension and then set it manually to be driven.

Basically add a permanent measurement to the sketch which then can also be used as a variable in other formulas.

My intention with this post was different.

As an example:

We have two lines which are constrained perpendicular to each other but are weirdly positioned and rotated in the drawing space (Not horizontal or vertical).

I now add a driven angular dimension between bot hlines which of course is then 90°.

Fusion needs to take the position, rotation and all other relevant constraints into account to calculate it.

It will solve the equation down to the perpendicular constraint and then use it and get a result of 90°.

If we add any other driven dimension it will solve it differently.

This solving process, or the final equation is what i would like to see.

[Marco.Takx]

Hi @an.niki,

Can you make a sample of explanation about the steps and at what point you are getting an incorrect sketch?

Just by reading your text and creating that sketch myself and deleting the Perpendicular constraint I can toggle the 80 deg as a dimension but don't see any strange behavior.

If my post answers your question Please use Accept as Solution & Kudos This helps everyone find answers more quickly! 

[an.niki]

Hi @Marco.Takx 

Maybe my first post was misleading.

I do not have a problem.

The sketch i showed in the picture is also working fine.

My main goal is to get a mathematical formula out of a constrained sketch (more precisely a driven dimension).

As an example i have added a fully constrained sketch of a 2D light reflection (in the first post).

The driven dimensions show the result of all constrains working together.

I would like to see how Fusion solves these mathematically.

[jeff_strater · Accepted solution]

@an.niki - @Marco.Takx is correct, there are no "calculations" for driven dimensions.  The driving dimensions, geometries, and geometric constraints are all solved together by the sketch solver inside Fusion.  This solver essentially solves a system of equations that describe the constraints, etc.  Then, once solved, the driven dimensions are measured from the solved geometry (the angle between two lines, for instance).  So, there is nothing to show here, since the solve is done numerically/programmatically.

[jeffescott]

All the equations are shown in the parameters drop down.

i think tho you mean if you click on the driven dimension.  It would show the precedents like in a spread sheet?

[an.niki]

Hi @jeffescott 

The parameters window only show the user parameter equations and the equations of the model parameters which i put in by myself.

Would be great if it would also show the equations for the model parameters which are solved by Fusion.

Showing the precedents like in a spreadsheet would be an option. Or be able to export it in any other way.

[an.niki]

Hi @jeff_strater 

You explained well whats happening, thanks!

I would still like to access what's happening in the solver and see it but i can imagine that it is too confidential for a user. 😅