Thanks, that makes sense. I realize that I should have read the help page for sign before I posted the quesiton :-)

Thanks, that makes sense. I realize that I should have read the help page for sign before I posted the quesiton :-)

Thanks to you, Alejandro, for confirming that there is a bug in match.

In theory match is useful for many purposes but the presence of bugs may make it less applicable i practice.

Best, Henning

Thanks to you, Alejandro, for confirming that there is a bug in match.

In theory match is useful for many purposes but the presence of bugs may make it less applicable i practice.

Best, Henning

No, there are no missing parentheses. The intension with my tiny example was to see if the match function could tell me what I knew already, namely that y = exp(-6*x)*k[1]*sin(4*x)+k[2]*cos(4*x) cannot be a solution for a homogeneous second order differential equation, diff(y,x,x)+B*diff(y,x)+C*y = 0. However, the reason why I submitted a question was not to get help in relation to second order DE. The reason was that I was a little puzzled by the fact that the match function returned results containing x, which was a main variable in the call to match. I expected match to return false, since no values of B, C, k1 and k2 would make the lhs of the DE zero for all x after inserting the indicated function y. I'm sure that I misunderstood something but I cannot figure out what it is.

Best, Henning

No, there are no missing parentheses. The intension with my tiny example was to see if the match function could tell me what I knew already, namely that y = exp(-6*x)*k[1]*sin(4*x)+k[2]*cos(4*x) cannot be a solution for a homogeneous second order differential equation, diff(y,x,x)+B*diff(y,x)+C*y = 0. However, the reason why I submitted a question was not to get help in relation to second order DE. The reason was that I was a little puzzled by the fact that the match function returned results containing x, which was a main variable in the call to match. I expected match to return false, since no values of B, C, k1 and k2 would make the lhs of the DE zero for all x after inserting the indicated function y. I'm sure that I misunderstood something but I cannot figure out what it is.

Best, Henning