LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Formula Node Error

Highlighted

I am entering this formula :

 

 

z = -10*log((10**((x)/10))-(10**(-(y)/10))); in the formula node.  An error is displayed. Error on line 1 is marked by a '#' character: "... = -10*log((10**((x)#/10))-(10**(-(y)/10"    Formula node: array indexing expected. Did not get it. Please provide me with a solution

Snip.PNG

 

 

 

0 Kudos
Message 1 of 7
(470 Views)
Highlighted

Hi Chhavi,

 

Did not get it.

So you wire an array to your formula node - and don't get the error ""array indexing expected"?

 

Why use a formula node at all?

check.png

Because of famous polymorphism you can easily replace the controls/indicators by arrays…

Best regards,
GerdW
CLAD expired, using LV2011SP1 + LV2017 (+LV2019 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

Message 2 of 7
(456 Views)
Highlighted

A for loop around the expression node would work too.

 

Indeed, no reason for the FN...

0 Kudos
Message 3 of 7
(407 Views)
Highlighted


 

You can process arrays in the formula node, but it's quite a hassle

 

2019-07-16_141319_formula_primitives.png

0 Kudos
Message 4 of 7
(396 Views)
Highlighted

I abhor the formula node for the simple reason that you have no chance for syntax error using native math primitives instead.  (My typing is, well... bad.)  😄

Bill
CLD
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
0 Kudos
Message 5 of 7
(355 Views)
Highlighted

I do like expression nodes for simple scaling, like going from mm to m and vice versa.

 

A typical bug with the formula node and expression node is related to the fact that we use commas as separators over here. And when you use a number with a comma, you can get a valid expression, but not a valid result:

 

y=x*12,34;

 

This results in y=12 for x=1, not y=12,34! 

 

0 Kudos
Message 6 of 7
(335 Views)
Highlighted

Moreover, you can't inline a subvi, which has an expression node or formula node within

 

that's the main reason we use those structures only for prototyping

here's my favorite: 

http://zone.ni.com/reference/en-XX/help/371361R-01/lvinstio/degrees_to_radians/

0 Kudos
Message 7 of 7
(330 Views)