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30 lines
545 B
OCaml
30 lines
545 B
OCaml
open Util
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open Lacaml.D
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type t =
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| Lowdin of Mat.t
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| Canonical of Mat.t
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| Svd of Mat.t
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let make_lowdin ?(thresh=1.e-12) ~overlap =
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let u_vec, u_val = diagonalize_symm overlap in
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Vec.iter (fun x -> if x < thresh then
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invalid_arg (__FILE__^": make_lowdin") ) u_val;
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let u_val = Vec.reci (Vec.sqrt u_val) in
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let u_vec' =
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Mat.init_cols (Mat.dim1 u_vec) (Mat.dim2 u_vec) (fun i j -> u_vec.{i,j} *. u_val.{j})
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in
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let result =
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gemm u_vec' ~transb:`T u_vec
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in
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Lowdin result
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let make = make_lowdin
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