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QCaml/Utils/DIIS.ml
2018-05-31 18:50:34 +02:00

62 lines
1000 B
OCaml

open Lacaml.D
open Util
type t =
{
p : Vec.t list;
e : Vec.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);
}
let next diis =
let e = Mat.of_col_vecs_list diis.e
and p = Mat.of_col_vecs_list diis.p
in
let a =
let rec aux m =
let a = Mat.make (m+1) (m+1) 1. in
a.{m+1,m+1} <- 0.;
ignore @@ lacpy ~b:a (gemm ~transa:`T ~m ~n:m e e);
if m > 1 && sycon (lacpy a) > 1.e-14 then
aux (m-1)
else a
in
aux diis.m
in
let m = Mat.dim1 a - 1 in
let c = Mat.make0 (m+1) 1 in
c.{m+1,1} <- 1.;
sysv a c;
gemm p c ~k:m
|> Mat.as_vec