Where does one find out what the error messages mean when trying to write a custom expression? I keep getting a syntax error and/or Missing statement error and don't know what it means. How am I supposed to know what I need to fix if I don't know what the error means? I am new to expressions etc and am getting frustrated with it and there's nowhere that I can see in the pdf's that can help me out.

Is there somewhere that has better write ups on how to write the expressions or that has examples for dummies like me?

There's documentation in there(expressions) that covers all the basics, but there's also a bit of an assumption that you've done some expressions before, be it in mathematics, programming, regex, whatever. There's reference, but little in the way of gently easing you into expressions in general. More often than not, it's silly syntax things like a missing bracket - but you need to know how to read an expression to find it.

I strongly recommend that if this is becoming overly frustrating for you that you try using CHOPs instead of expressions. That's precisely what it was designed for: to allow people who aren't comfortable writing great long expressions to use a network based channel editor…this also gives you the advantage of being able to see representations of your expressions in a graph. Writing expressions is great if you're used to it, especially for a quick and dirty solution - but CHOPs gives you more structure and control at the expense of a little more setup time.

Using expressions within a complicated app like Houdini isn't really the best place to learn math expressions…

Alternatively, if you have a specific example of something you're struggling to solve, I would suggest posting it here and I'll bet several people will jump all over it…

Cheers,

J.C.

I am working on an assignment that is for the online class over at 3dBuzz and I need an expression in order to complete the task needed. I followed and understood Buzz's vtm with the expressions he used. I posted this problem over at odforces site as well as the online class forum at 3dBuzz but I think most people are away for the holidays as I am not getting much help. If I don't get help there by Friday, I'll try to post the long explanation over here.

So, a syntax error has to do with missing brackets or wrong punctuations? What does the ‘missing statement’ mean?

Edit: I finally wrote my custom expression successfully but it still didn't work when I put it in the ry of my door transform. A fellow Buzz student showed me what was wrong in the expression and now it works. I had this: execute (“setenv door=chf(”Rotation“,ch(”../xfrmBall/tx“))”). Which would have shown as: execute (“setenv door=chf(”)) (it would have thought the expression was done after the second “). I needed to add / before each ” except the last one. Also my “return” part was wrong; instead of return $Door, I should have put, return eval($Door) since $Door is a string and not a value; my $Door in the expression was: chf(“Rotation”,ch(“../xfrmBall/tx”)) not a number. The eval ($Door) would compute the value of the $Door's string expression. This probably doesn't make any sense to most. I thought I would put this here if anyone was interested in knowing. I hate it when I read threads where the person doesn't let you know if a solution was found or not.