Posts: 294

Threads: 32

Joined: Jul 2005

Hi Luiz: I'll try to answer your questions. If you solve a system in the 15C, you'll get a set of solution even when the system have no solution. For instance: [[1][0]]/[[1 2][1 2]] gives you the next result matrix: [[2e10][-1e10]]. I think the key for this behaviour is in page 150 of the manual:"If the matrix...does not have an inverse...the calculated inverse is the inverse of a matrix close to the original..." I don't like this... I'd prefer get an error saying clearly that the matrix does not have an inverse, so the system does not have one solution (perhaps infinite solutions, perhaps no solution). We can get this information calculating the determinant of matrix of coefficients. We'll get 1e-10 in this case, value that "is" 0. But if I'd have the reduced matrix (triangular or Gauss form) I could see if the last line has only 0's (infinite solutions) or all 0's but the last one, (no solution). Recently I have programmed the reduction in an old Casio fx 4000p: I would like to use the matrix features of the 15c for calculating without programming.I hope you understand something in this mess...

Regrads. Raul