id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
185	IS4DVAR preconditioning	arango	arango	"We are now working on the preconditioning for the '''IS4DVAR''' algorithms.  Andy Moore coded the spectral preconditioning.

I added two new files ('''def_lanczos.F''' and '''wrt_lanczos.F''') to process the Lanczos vectors. We need both Lanczos vectors and Hessian eigenvectors to compute the preconditioning.  More updates are coming soon.

Corrected a bug in the observation sensitivity driver.  We need to added the spatial convolutions to the Lanczos vectors used to initialize the tangent linear model.  The Lanczos vectors are in minimization space ('''v-space'''). Many thanks to Andy Moore for finding this problem"	upgrade	closed	major	Adjoint Based Algorithms	Adjoint	3.2	Done