Determinant function in Mathematica

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Determinant function in Mathematica*From*: Steven M. Christensen <stevec at yoda.physics.unc.edu>*Date*: Wed, 8 Apr 92 23:44:20 EDT

I wonder if someone in this group could shed some light on why the Det[] function in Mathematica requires as much time as it does. I have been trying to compute the symbolic determinant of a 4x4 matrix and Mma has been running for about 18 hours with no answer. This seems like a large amount of time for such a simple problem. I talked to another person doing similar calculations and he ran into the exact same problem with both Mma and Maple. Has anybody out there found a fix for this problem? I would like to hear from people who have perhaps written Determinant functions that take full advantage of sparse matrices. The problem I am looking at is that of computing saddle-node and Hopf bifurcations in nonlinear ordinary differential equations. I need to be able to take the determinant of the Jacobian with the fixed point and parameter values left unspecified. Thanks for your help Tony Varghese