# [Scilab-users] expression block in xcos gives “answer given for scilab expression is wrong” error Classic List Threaded 2 messages  As I have originally explained in  this post   I'm trying to put the SciLab expression: sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) / m)^0.5 but I get this error message: answer given for scilab expression is incorrect... I would appreciate if you could help me know what is the problem and how I can solve it. Maybe I should use a different block? -- Sent from: http://mailinglists.scilab.org/Scilab-users-Mailing-Lists-Archives-f2602246.html_______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users Hello Farimani, Le 19/02/2019 à 10:47, farimani a écrit : ```As I have originally explained in this post I'm trying to put the SciLab expression: sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) / m)^0.5 but I get this error message: answer given for scilab expression is incorrect... I would appreciate if you could help me know what is the problem and how I can solve it. Maybe I should use a different block?``` Copy/pasting your formula in the console: ```[Fm, M, m, k] = (1,1,1,1); [u1, u2] = (1,2); r = sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /m)^0.5; --> r = sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /m)^0.5; r = sign(u2 – u1) * (2 * ((Fm + M) * abs(u2 – u1) + k * (u2^2 – u1^2) / 2) /m)^0.5; ^~~^ Error: syntax error, unexpected identifier, expecting "," or ) ``` Puzzling... Hard to find why, but finally: You have likely copy/pasted this formula from a "formatted" document, maybe a web site, etc. Then, the included "–" character is not the mathematical minus, that is "-". This puzzles the Scilab's parser. If you input the same formula, just replacing the hyphens with the true minus, it works, in the console as well as in Xcos. --> r = sign(u2 - u1) * (2 * ((Fm + M) * abs(u2 - u1) + k * (u2^2 - u1^2) / 2) /m)^0.5  r  =    2.6457513 HTH Samuel _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users