List of things named after Jacques Hadamard

These are things named after Jacques Hadamard (1865–1963), a French mathematician. (For references, see the respective articles.)

Theorems, lemmas, and conjectures
Many of these results are sometimes called "Hadamard's theorem".
 * Cartan–Hadamard theorem, a statement in Riemannian geometry concerning the structure of complete Riemannian manifolds of non-positive sectional curvature
 * Cartan–Hadamard conjecture, an open problem in Riemannian geometry and geometric measure theory concerning the generalization of the classical isoperimetric inequality to spaces of nonpositive sectional curvature
 * Cauchy–Hadamard theorem, a statement in complex analysis describing the radius of convergence of a power series
 * Hadamard's inequality, a bound on the determinant of a matrix whose entries are complex numbers in terms of the lengths of its column vectors
 * Hermite–Hadamard inequality, a bound on the mean value of a convex function in an interval in terms of the value it takes at the mid-point and ends of interval
 * Hadamard's lemma, a result closely related to the first-order term in Taylor's theorem
 * Ostrowski–Hadamard gap theorem concerning the analytic continuation of complex power series
 * Hadamard three-circle theorem, concerning the maxima of holomorphic functions within concentric circles in the complex plane.
 * Hadamard three-lines theorem, concerning the maxima of holomorphic functions defined in regions bounded by parallel lines in the complex plane.
 * Hadamard's embedding theorem

Mathematical objects and definitions

 * Hadamard product:
 * entry-wise matrix multiplication
 * an infinite product expansion for the Riemann zeta function
 * Hadamard code
 * Hadamard's dynamical system
 * Hadamard manifold
 * Hadamard matrix
 * Hadamard space
 * Hadamard Transform and Hadamard gate
 * Hadamard variance
 * Hadamard's gamma function

Equations, problems, and methods

 * Hadamard–Rybczynski equation
 * Hadamard's maximal determinant problem
 * Hadamard's method of descent
 * Hadamard regularization