how to plus fractions in LabVIEW

[EduU]

Good morning!

I have on question, How can I plus some fractions in LabVIEW?

Example:

(40/100*s+1) + (50/200*s^2+102*s+1)

How can I make this operation in LabVIEW??

Thanks!

[Christian Mergl]

Hey,

Think in dataflow!

And see attached jpg.

Christian

[elset191]

They look like constants to me.  If that's the case use .4 and .25, instead of doing 40/100 and 50/200 every time.

[Christian Mergl]

Hey Tim,

I just used the calculations to show the possible implementation in LV. Though you are right to use constants instead of the 40/100 and so on.

Christian

[EduU]

Thanks for the help!

I thought have an easier way to make it.

and this isn't constant guys

it's because I only make an example to learn how do it

I will try here

[elset191]

---

Christian_M wrote:

I just used the calculations to show the possible implementation in LV. Though you are right to use constants instead of the 40/100 and so on.

---

I figured as much.  I was saying it for the OP, because he seems to be new at LV.  I know I've wasted a lot of time starting to code the division before I realized it was just a constant.

[JHourigan]

Try using a formula node from the structures palette.  You'll quickly gain a sense of when it's best to use the operation VIs and when to formula nodes (usually for longer calculations - where using the operations VIs creates a mess).  The syntax is a little different than shown in your posting, but the help files will guide the way.

[Hecuba]

Hi EduU,

I believe that the best way to implement your formula is using the "Expression Node" in the Numeric Palette since you have only one variable (s).

By the way, the Christian_M implementation has a little mistake, see the attached snapshot.

 

Hecuba

[Christian Mergl]

@Hecuba   Ups, I see, it was  s^2 and I did s*2, thank you!

[Barp]

Edu,

It those equation are Transfer Function in the "s" domain, you should consider using the Control Design and Simulation Module. Once you created the transfer function, you can see the result and do other operations like obtaining the Frequency Response or simulate its result. Here is the code for adding the two transfer functions you described above

Let me know if this answer your question!

Message Edited by Barp on 10-27-2009 08:12 AM