  We derive bounds for the minimum and maximum eigenvalues and the spectral
condition number of matrices for isogeometric discretizations of elliptic
partial differential equations in an open, bounded, simply connected Lipschitz
domain $\Omega\subset \mathbb{R}^d$, $d\in\{2,3\}$. We consider refinements
based on mesh size $h$ and polynomial degree $p$ with maximum regularity of
spline basis functions. For the $h$-refinement, the condition number of the
stiffness matrix is bounded above by a constant times $ h^{-2}$ and the
condition number of the mass matrix is uniformly bounded. For the
$p$-refinement, the condition number grows exponentially and is bounded above
by $p^{2d+2}4^{pd}$ and $p^{2d}4^{pd}$ for the stiffness and mass matrices,
respectively. Rigorous theoretical proofs of these estimates and supporting
numerical results are provided.
