# [LON-CAPA-users] formula response with cas

**H.K. Ng
**
lon-capa-users@mail.lon-capa.org

*Wed, 22 Oct 2008 10:43:40 -0400*

Thanks for the feedback.
>*Hi
*>*
*>*H.K. Ng wrote:
*>*
*>>*Hi,
*>>*I am writing some formula response problems and would like to use
*>>*maxima to compare two algebraic expressions. Basically, the
*>>*questions will ask the students to solve the problems algebraically
*>>*and then enter the expression. Some questions:
*>>*1. What is the maxima function to use in this case? Using Peter's
*>>*writeup, ratsimp works but does not seem appropriate when it is a
*>>*comparison of two expressions.
*>>*2. Also, reading Peter's writeup, it says that the expression is
*>>*passed to &implicit_multiplication function so that it inserts the
*>>*"*" symbol where a multiplication is implied. However, when I enter
*>>*v^2+2g(a-b) it is not graded correctly. On the other hand
*>>*v^2+2*g*(a-b) is graded correctly. What I am missing here?
*>*If you send me the code, I will have a look. Seems weird.
*
I found out the reason (after reading Justin's writeup) 2g(a-b) can
be interpreted as 2 times the function g(a-b), so using g2(a-b) is
ok. Maybe, we need a flag to indicate that these are all factors, no
function in the implicit_multiplication call - to make it easier for
the students??
>>*3. How do I use greek symbols for an expression, both in the coded
*>>*answers and as input in the answer box? Drag math does insert greek
*>>*symbols but there doesn't seem to be a way to directly type it in?
*>*Within loncapa dragmath is configured to convert to maxima syntax.
*>*maxima swallows almost every variable name. So using alpha, beta,
*>*etc. would be fine. Problem is, you have tell non-dragmath users
*>*that they have to enter alpha for \alpha etc.
*>*
*>*Along the road of this will be the question whether we should have a
*>*loncapa standard on entering pi ...
*
I would definitely say that having a standard way of entering pi etc
is preferred. However, as it stands now putting theta does not
display the symbol (just the word). Is there a way to show the symbols?
-hk