Absolute Value in Equation?

[laxman12786]

Hello, I am trying to generate a datum curve based on an equation, but am having a problem.



What I'm trying to do is generate only the "bottom" of a sine-wave that
repeats (basically a bunch of connected goooves/troughs). I'm
trying to accomplish this by using the abs() around my wave function
and making my period twice as long (i.e. each "wave" will turn into 2
"grooves").



When I try this I get an error that says: "abs" cannot be used in equations.



Is there a better way to accomplish what I'm trying to do here?



Thanks!

 

[dr_gallup]

From WF2 help on Datum Curve From Equations:
Note: You
cannot use the following statements in an equation that defines a datum curve:
abs, ceil, floor, else, extract, if, endif, itos, and search.Maybe just make the 1st half wave & then copy or pattern?

y=sin(180*(t-1))
x=t
z=0

 

[laxman12786]

Thanks...I ended up looking through the help and found the same
thing. I've already modeled the half wave and patterned.
It's a mess, but I guess it's all I can do.



Thanks for the reply though!

 

[kschauer]

I haven't tried it myself, but couldn't you just square the numer and then take the square root?
An Excel statement would look like this:
x=(^2)^0.5)

Now just put your equation into it.
Any other ideas??

 

[laxman12786]

Definitely an option that I didn't think of...



Either way though, I've already gone with the method above and
completed the model. Maybe if I get a bit of free time later or
have to revise the model I'll try the square/square-root way to see if
it works.



Thanks!

 

[dr_gallup]

No, I tried squaring and taking the root, Pro/E said:


Curve could not be constructed.

 

[dr_gallup]

I tried this also, which are valid relations, but again Pro/E could not construct the curve:

IF t<.5
y=-sin(360*t)
ELSE
y=sin(360*t)
ENDIF
x=2*t
z=0

Oops, nevemind, I forgot my own post above that said you can't use IF statements in datum curve relations.


Edited by: dr_gallup

 

[laxman12786]

Yeah, I tried something similar before posting my original question. Do you by chance know why Pro/E would exclude the use of abs(), if, etc. in curve equations?

 

[jeff4136]

> would exclude the use of ...

Nope, but I imagine Pro/E will hiccup at the full multiplicity knots required to create the kinks caused by the inverted half wave.

A little more info on requirments ~might~ ellicit some additional suggestions. Wondering if two offset waves superimposed and trimmed or just halving the period and offsetting Y will serve your purposes?

 

[laxman12786]

Well, I was actually modeling the parts for someone in a different department, and completed them with the first method that is listed above by dr_gallup. He's happy with the parts, so I'm happy too.


I used:


x=.269t


y=.0025*-sin(180t)


z=0


and just patterned it...seems to work for what I need it to.
Edited by: laxman12786