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QCaml/linear_algebra/lib/diis.ml

68 lines
1.2 KiB
OCaml

type 'a t =
{
p : 'a Vector.t list;
e : 'a Vector.t list;
m : int;
mmax : int;
}
let make ?mmax:(mmax=15) () =
assert (mmax > 1);
{
p = [];
e = [];
m = 0 ;
mmax;
}
let append ~p ~e diis =
let update v l =
if diis.m < diis.mmax then
v :: l
else
match List.rev l with
| [] -> assert false
| _ :: rest -> v :: List.rev rest
in
{ diis with
p = update p diis.p;
e = update e diis.e;
m = min diis.mmax (diis.m+1);
}
type nvec
type one
let next diis =
let e = Matrix.of_col_vecs_list diis.e
and p = Matrix.of_col_vecs_list diis.p
in
let a =
let rec aux m =
let a = Matrix.make (m+1) (m+1) 1. in
let ax = Matrix.to_bigarray_inplace a in
ax.{m+1,m+1} <- 0.;
Matrix.gemm_tn_inplace ~c:a ~m ~n:m e e;
if m > 1 && Matrix.sycon a > 1.e-14 then
(aux [@tailcall]) (m-1)
else a
in
aux diis.m
in
let m = Matrix.dim1 a - 1 in
let c : (nvec,one) Matrix.t = Matrix.make0 (m+1) 1 in
let cx = Matrix.to_bigarray_inplace c in
cx.{m+1,1} <- 1.;
Matrix.sysv_inplace a ~b:c ;
Matrix.gemm_nn ~k:m p c
|> Matrix.as_vec_inplace
|> Vector.relabel
(*
|> Vector.relabel
*)