Error -23027 in parametric graph

[T16626]

First off, I'm not even sure if what I have been attempting is feasible, so please tell me if it by chance is not possible to finish this. Nonetheless, here goes my attempt at solving my problem:

I am trying to display a parametric graph (form x(t)=... and y(t)=...). My front panel contains an XY Graph. My back panel is pictured below (and attached as a VI Snippet PNG file):

:

However, my functions are extremely complex (3 printed pages) parametric plot, (involving the Heaviside step, sign function, and lots of trig). When I first received the error ("-23027, more than one variable"), I thought I may have mistyped an element in the equation, but after extensive searching, I could not find a single letter out of place. This begs my question:

How can there be more than one variable if the only times I use letters in the strings that contain the formula are in "sqrt", "sin", "sign", "cos", and "step" (all functions, to my knowledge) and of course, the sole variable "t"?

Here is the basic idea of what I'm trying to pull off. 

http://blog.wolframalpha.com/2013/05/17/making-formulas-for-everything-from-pi-to-the-pink-panther-t...

(my "picture" isn't as complex as most of the examples on wolfram alpha)

If any clarification is needed, I'm happy to post it. I just don't want to unnecessarily clutter this question with my 3 page parametric formula.

Thanks a million,

T16626

[GerdW]

Hi T,

with some basic debugging (highlighting/probes) you would have noticed an error -23083 ("bracket problem at end of string" [a rough translation of German message]) in the first step of formula analysis...

You're free to dig in even deeper than I did!

[T16626 · Accepted solution]

Being somewhat new to LabView, I had no idea that "probing" existed. However, it is a great tool for debugging, (so far as I can tell), and although it didn't help me find the problem directly, it did help me eliminate some possibilities.

Here is what I did wrong in the VI snippet attached to the original question (which is still incorrect):

1. I left spaces instead of multiplying using the '*' (asterisk).
2. I wrote the sign function "sgn(..." instead of "sign(..."

Thanks for your help GerdW.

Also, I have attached my working VI Snippet to this post, while leaving the original up for people to use as an example of what NOT to do.

Cheers,

T16626

EDIT: I recommend changing the "number of points" value on the "Eval X-Y(t) Optimal Step" sub-VI to something much higher than the default 10, which produces a grapht that is a bit... inaccurate... if I may say so.