get_coercivity.m

function coercivity_alpha = get_coercivity(model,K,W)
%function coercivity_alpha = get_coercivity(model,K,W)
%
% This function computes the coercivity constant alpha for a discrete
% operator K with respect to the inner product matrix (mass matrix) W.
%
% input:
%  - K: Operator Matrix
%  - W: inner product matrix
%
% output:
%  - coercivity_alpha: coercivity constant.
%
% coercivity_alpha is the smallest Eigenvalue of:
% K*v = lambda*W*v
%
% Oliver Zeeb, 2013/11/18

%coercivity always defined on the symmetric part:
K = (K+K')/2;
coercivity_alpha = eigs(K,W,1,'sa');