I'm no mechanical engineer, but are there any good failure analysis for stresses on different shapes of material in either maple or maplesim?  

I recall something, maybe, in maplesim or maple, possibly an application where I think I saw a graph with force increasing and then levelling off indicating the material broke?  I'm not exactly sure.  Maybe there are some posts somewhere but can't seem to find any. 

Performing a search brought some results from wamp.mapleprimes.com. 

I clicked on it and firefox gave me a warning.  Is wamp.mapleprimes.com a legitamate site???

What am I missing here?  I type in a simple differential equation and I get .. unable to parse error.

In a procedure what is the way to only allow specific values in a variable?

ie/

change:=proc(a::integer, b={10,20,30})#only values 10, 20 and 30 allowed for variable b
  a*b;
end proc:

Trying to find a formula such that when n is negative the value is +1 and when n is positive the value is 0, without using an if statement.