revised the diff_coeffs method, added code that decreased the number of differentiation points when there's a warning about near-singular matrix; implemented the zeros method, handling symbolic and numeric; implemented the triu method, for multi-dimensional matrices; implemented the symmetricidx method, that returns the indexes of symmetry in multi-dim matrices; implemented the makesymmetric method; implemented a bunch of symbolic utilities: factorize, defactorize, matvecmul, cs2k and latex_def.
revised the diff_coeffs method, added code that decreased the number of differentiation points when there's a warning about near-singular matrix; implemented the zeros method, handling symbolic and numeric; implemented the triu method, for multi-dimensional matrices; implemented the symmetricidx method, that returns the indexes of symmetry in multi-dim matrices; implemented the makesymmetric method; implemented a bunch of symbolic utilities: factorize, defactorize, matvecmul, cs2k and latex_def.

jgte/orb,jgte/orb,jgte/orb,jgte/orb,jgte/orb