Evaluate component

Hi everyone and many thanks for taking the time for reading my question.

My problem is that i really don't know how to use correctly the evaluate component because sometimes it works and others don't.

Actually i'm developing a simple definition, but as long as i write something in the expression editor it turns red and somethimes i make the same process and it works without problem.

maybe im making a simple mistake but i'm new at GH.

Kind regards.

Replies to This Discussion

Permalink Reply by David Rutten on September 1, 2017 at 3:47pm

Grasshopper expressions are loosely based on VBScript syntax, with a few additional features. When you have an expression which either contains a syntactic problem (missing bracket for example) then you should get an error that describes the problem.

Other times the expression is syntactically valid but still fails when it is evaluated because the data types of variables are not consistent with some operation. For example you can use the minus symbol to subtract two numbers, but you cannot subtract text from numbers. Hence "a-b" is a valid expression only when a and b are in fact subtractable.

Without a specific example that fails I cannot be more informative though.

Permalink Reply by Alquimio on September 12, 2017 at 7:52am

Hi D. Rutten, i replied as soon as i could, once again many thanks for taking the time to answer my question, bun i have the same problem with the evaluate component.

Image 1- I develop the "GH definition" without problem, and i conect any componen to evaluate's input.

Image 2- it seems to be alright but inmediately turns red; It does not matter if i use the expression editor or a "panel".

Image 3- I closed Rhinoceros, i did the same expression and i got the same result, bun then i changed to another more simple expression and it worked,

Image 4-I change to the expression desired and it work.

So my question is about if im making a mistake or theres a problem with my software...

Kind regards.

Permalink Reply by Joseph Oster on September 12, 2017 at 8:14am

Read this first! How to get help on this forum.

There is a small box at the top-right corner of the red 'Eval' component that contains the error message; click on it and tell us what it says?

Permalink Reply by Joseph Oster on September 12, 2017 at 8:30am

Edit: apparently part of my last post was lost...

How did you enter those superscripts? Try 'Pow(x,2)' and 'Pow(y,2)'.

Like this:

Permalink Reply by Hyungsoo Kim on September 12, 2017 at 8:28am

Permalink Reply by Alquimio on September 12, 2017 at 8:38am

Hi, my mistake, i didn't put the "+" but anyway sometimes it works and other doesn't, and in the following image, the one which has the expression editor open, shows my question that sometimes i make the same steps and turns red.
in other example i wrote x potence 2, and as simple as this the component turned red.

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