Allow pinv to work on Diagonal Matrices with a tolerance (bug #41546). * pinv.cc (Fpinv): Validate tolerance argument and pass it through to pseudo_inverse(). CDiagMatrix.h, dDiagMatrix.h, fCDiagMatrix.h, fDiagMatrix.h: Redefine prototype for pseudo_inverse to accept a single argument for tolerance. * CDiagMatrix.cc (pseudo_inverse), dDiagMatrix.cc(pseudo_inverse), fCDiagMatrix.cc(pseudo_inverse), fDiagMatrix.cc(pseudo_inverse): Use std::abs(elem) to get magnitude of element and only invert if value is greater than tolerance.

gnulib-hg = gnulib-hg