Grigory, If you do *not* include a samples attribute in the formularesponse tag, then maxima will be used to compare the submitted formula with the expected answer. This became the default starting with LON-CAPA 2.4.0 (June 2007).
However, if you include sample points in the formularesponse item, and your answer includes pi, see the example here: help.loncapa.org/fom/cache/361.html which shows how to include pi as a "variable" in the sampling points. For example, the following will grade as correct a submission of: 1/sqrt(4*pi^2*L*C) <problem> <script type="loncapa/perl"> $ans = "1/(2*pi*sqrt(L*C))"; </script> <startouttext /> <p>Enter <m>$ \frac{1}{\sqrt{4\cdot\pi^{2} \cdot L\cdot C}} $</m></p> <endouttext /> <formularesponse answer="$ans" samples="pi,L,C@$pi,.1,.1:$pi,100.,100.#1"> <responseparam name="tol" type="tolerance" default="0.00001" description="Numerical Tolerance" /> <textline readonly="no" size="25" spellcheck="none" /> </formularesponse> </problem> See: loncapa.msu.edu/adm/help/Formula_Response_Sampling.hlp for additional information about the format to use for sampling points. Stuart Raeburn LON-CAPA Academic Consortium ________________________________________ From: LON-CAPA-users <lon-capa-users-boun...@mail.lon-capa.org> on behalf of SIMIN, GRIGORY <si...@engr.sc.edu> Sent: Thursday, November 21, 2019 11:03 AM To: Discussion list for LON-CAPA users Subject: [LON-CAPA-users] Formula response won't recognize "pi" Hi all! I've found a strange issue in some problems requiring formula response. I have a simple question to enter the formula for the resonant frequency. An example of correct answer is (in other variations the formula could be a bit more complex than this one) 1/(2*pi*sqrt(L*C)) The correct solution is checked by sampling L and C values. When I am entering the answer, I can see that LON-CAPA recognizes it because it displays the formatted formula as I am entering it: [cid:image003.jpg@01D5A05B.449F5B20] But when I press submit, I got the response: “unable to understand formula” By experimenting with this, I found that the issue happens because of “pi” being a part of the answer. If pi is replaced with 3.141, everything would work. But it feels weird asking students to enter 3.141 instead of pi; besides, I don’t even want to give them a hint that pi is a part of the answer. Why is this happening? Apparently LON-CAPA knows what “pi” means because it displays it correctly. Thanks! Grigory
_______________________________________________ LON-CAPA-users mailing list LON-CAPA-users@mail.lon-capa.org http://mail.lon-capa.org/mailman/listinfo/lon-capa-users