Cannot evaluate equation  topic started 6/26/2001; 1:40:47 PM last post 6/26/2001; 3:33:52 PM 

Michael Gage  Re: Cannot evaluate equation 6/26/2001; 3:33:52 PM (reads: 1080, responses: 0) 
Hi, In WeBWorK all evaluation (so far at least) is done numerically. Two functions are "equal" if they give the same value on 5 or 6 randomly selected points. (It's somewhat surprising how well this works.) You can adjust the domain on which the randomly selected points are chosen. The best reference is http://webhost.math.rochester.edu/webworkdocs/docs/pglanguage/manpages/fun_cmp fun_cmp is a replacement for multivar_function_cmp (and a bunch of similar functions) The options are described on the space above. fun_cmp($ans, var=>['r','h'], limits=>[[1,2],[0,.9]] ) would probably work since r^2h^2 is positive on that domain. the default limits are [[0,1], [0,1]] which will cause trouble in this case.  Mike 