mirror of
https://github.com/TREX-CoE/qmckl.git
synced 2025-01-03 18:16:28 +01:00
* Moved Helper functions to the end
* Typo fixed
This commit is contained in:
Francois Coppens
parent
ef04e3df9b
commit
dcd6428c50
@ -4,7 +4,7 @@
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Low- and high-level functions that use the Sherman-Morrison and
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Woodbury matrix inversion formulas to update the inverse of a
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non-singualr matrix
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non-singular matrix
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* Headers
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#+begin_src elisp :noexport :results none :exports none
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@ -27,178 +27,6 @@ int main() {
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#+end_src
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* Helper Functions
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Helper functions that are used by the Sherman-Morrison-Woodbury kernels.
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These functions can only be used internally by higher level functions.
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** ~qmckl_slagel_splitting~
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:PROPERTIES:
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:Name: qmckl_slagel_splitting
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:CRetType: double
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:FRetType: double precision
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:END:
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~qmckl_slagel_splitting~ is used internally to apply a list of rank-1 updates while splitting an update if necessary.
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In case of a split it applies the first half of the update while putting the second half in waiting queue to be applied at the end.
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For a given update $u_j$ we define a threshold value $\epsilon_j$, which is the minimum value of
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$1+v_j^TS^{-1}u_j$ for a non-singular matrix $S$. If $1+v_j^TS^{-1}u_j \geq \epsilon_j$,
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the update is applied as usual. Otherwise, $u_j$ will be redefined as $\frac{u_j}{2}$, and the other half
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(to be applied at the end) will be defined using vectors $\frac{u_{j'}}{2}$ and $v_{j'}^T=v_{j'}^T$.
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#+NAME: qmckl_slagel_splitting_args
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| uint64_t | Dim | in | Leading dimension of Slater_inv |
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| uint64_t | N_updates | in | Number of rank-1 updates to be applied to Slater_inv |
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| double | Updates[N_updates*Dim] | in | Array containing the rank-1 updates |
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| uint64_t | Updates_index[N_updates] | in | Array containing positions of the rank-1 updates |
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| double | breakdown | in | Break-down parameter on which to fail or not |
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| double | Slater_inv[Dim*Dim] | inout | Array containing the inverse Slater-matrix |
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| double | later_updates[Dim * N_updates] | inout | Array containing the split updates for later |
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| uint64_t | later_index[N_updates] | inout | Array containing the positions of the split updates for later |
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| uint64_t | later | inout | Number of split updates for later |
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*** Requirements
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- ~Dim >= 2~
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- ~N_updates >= 1~
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- ~Updates~ is allocated with at least $1 \times 2 \times 8$ bytes
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- ~Updates_index~ is allocated with at least $1 \times 8$ bytes
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- ~breakdown~ is a small number such that $0 < breakdown << 1$
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- ~Slater_inv~ is allocated with at least $Dim \times Dim \times 8$ bytes
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- ~later_updates~ is allocated with at least $1 \times 2 \times 8$ bytes
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- ~later_index~ is allocated with at least $1 \times 8$ bytes
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- ~later >= 0~
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*** C header
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#+CALL: generate_c_header(table=qmckl_slagel_splitting_args,rettyp=get_value("CRetType"),fname=get_value("Name"))
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#+RESULTS:
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#+begin_src c :tangle (eval h_func) :comments org
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qmckl_exit_code qmckl_slagel_splitting_c (
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const uint64_t Dim,
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const uint64_t N_updates,
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const double* Updates,
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const uint64_t* Updates_index,
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const double breakdown,
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double* Slater_inv,
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double* later_updates,
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uint64_t* later_index,
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uint64_t* later );
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#+end_src
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*** Source Fortran
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*** Source C
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#+begin_src c :tangle (eval c) :comments org
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#include <stdbool.h>
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#include <math.h>
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#include "qmckl.h"
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qmckl_exit_code qmckl_slagel_splitting_c(uint64_t Dim,
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uint64_t N_updates,
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const double *Updates,
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const uint64_t *Updates_index,
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const double breakdown,
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double *Slater_inv,
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double *later_updates,
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uint64_t *later_index,
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uint64_t *later) {
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// #ifdef DEBUG // Leave commented out since debugging information is not yet implemented in QMCkl.
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// std::cerr << "Called slagel_splitting with " << N_updates << " updates" << std::endl;
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// #endif
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double C[Dim];
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double D[Dim];
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uint64_t l = 0;
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// For each update
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while (l < N_updates) {
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// C = S^{-1} x U_l
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for (uint64_t i = 0; i < Dim; i++) {
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C[i] = 0;
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for (uint64_t j = 0; j < Dim; j++) {
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C[i] += Slater_inv[i * Dim + j] * Updates[l * Dim + j];
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}
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}
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// Denominator
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double den = 1 + C[Updates_index[l] - 1];
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if (fabs(den) < breakdown) {
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// U_l = U_l / 2 (do the split)
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for (uint64_t i = 0; i < Dim; i++) {
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later_updates[*later * Dim + i] = Updates[l * Dim + i] / 2.0;
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C[i] /= 2.0;
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}
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later_index[*later] = Updates_index[l];
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(*later)++;
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den = 1 + C[Updates_index[l] - 1];
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}
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double iden = 1 / den;
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// D = v^T x S^{-1}
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for (uint64_t j = 0; j < Dim; j++) {
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D[j] = Slater_inv[(Updates_index[l] - 1) * Dim + j];
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}
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// S^{-1} = S^{-1} - C x D / den
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for (uint64_t i = 0; i < Dim; i++) {
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for (uint64_t j = 0; j < Dim; j++) {
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double update = C[i] * D[j] * iden;
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Slater_inv[i * Dim + j] -= update;
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}
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}
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l += 1;
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}
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return QMCKL_SUCCESS;
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}
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#+end_src
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*** Performance
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This function performce better for cycles with 1 rank-1 update and with a high fail-rate.
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** C interface :noexport:
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#+CALL: generate_c_interface(table=qmckl_slagel_splitting_args,rettyp=get_value("FRetType"),fname=get_value("Name"))
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#+RESULTS:
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#+begin_src f90 :tangle (eval f) :comments org :exports none
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integer(c_int32_t) function qmckl_slagel_splitting &
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(Dim, N_updates, Updates, Updates_index, breakdown, Slater_inv, later_updates, later_index, later) &
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bind(C) result(info)
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use, intrinsic :: iso_c_binding
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implicit none
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integer (c_int64_t) , intent(in) , value :: Dim
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integer (c_int64_t) , intent(in) , value :: N_updates
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real (c_double ) , intent(in) :: Updates(N_updates*Dim)
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integer (c_int64_t) , intent(in) :: Updates_index(N_updates)
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real (c_double ) , intent(in) , value :: breakdown
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real (c_double ) , intent(inout) :: Slater_inv(Dim*Dim)
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real (c_double ) , intent(inout) :: later_updates(Dim * N_updates)
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integer (c_int64_t) , intent(inout) :: later_index(N_updates)
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integer (c_int64_t) , intent(inout) :: later
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integer(c_int32_t), external :: qmckl_slagel_splitting_c
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info = qmckl_slagel_splitting_c &
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(Dim, N_updates, Updates, Updates_index, breakdown, Slater_inv, later_updates, later_index, later)
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end function qmckl_slagel_splitting
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#+end_src
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*** Test :noexport:
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This kernel does not have an explicit test because it is only used internally by higher-level Sherman-Morrison-Woodbury kernels.
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* Naïve Sherman-Morrison
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@ -691,6 +519,7 @@ for (unsigned int i = 0; i < Dim; i++) {
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assert(rc == QMCKL_SUCCESS);
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#+end_src
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* Woodbury 3x3
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** ~qmckl_woodbury_3~
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@ -1761,6 +1590,181 @@ for (unsigned int i = 0; i < Dim; i++) {
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assert(rc == QMCKL_SUCCESS);
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#+end_src
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* Helper Functions
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Helper functions that are used by the Sherman-Morrison-Woodbury kernels.
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These functions can only be used internally by higher level functions.
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** ~qmckl_slagel_splitting~
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:PROPERTIES:
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:Name: qmckl_slagel_splitting
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:CRetType: double
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:FRetType: double precision
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:END:
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~qmckl_slagel_splitting~ is used internally to apply a list of rank-1 updates while splitting an update if necessary.
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In case of a split it applies the first half of the update while putting the second half in waiting queue to be applied at the end.
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For a given update $u_j$ we define a threshold value $\epsilon_j$, which is the minimum value of
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$1+v_j^TS^{-1}u_j$ for a non-singular matrix $S$. If $1+v_j^TS^{-1}u_j \geq \epsilon_j$,
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the update is applied as usual. Otherwise, $u_j$ will be redefined as $\frac{u_j}{2}$, and the other half
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(to be applied at the end) will be defined using vectors $\frac{u_{j'}}{2}$ and $v_{j'}^T=v_{j'}^T$.
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#+NAME: qmckl_slagel_splitting_args
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| uint64_t | Dim | in | Leading dimension of Slater_inv |
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| uint64_t | N_updates | in | Number of rank-1 updates to be applied to Slater_inv |
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| double | Updates[N_updates*Dim] | in | Array containing the rank-1 updates |
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| uint64_t | Updates_index[N_updates] | in | Array containing positions of the rank-1 updates |
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| double | breakdown | in | Break-down parameter on which to fail or not |
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| double | Slater_inv[Dim*Dim] | inout | Array containing the inverse Slater-matrix |
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| double | later_updates[Dim * N_updates] | inout | Array containing the split updates for later |
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| uint64_t | later_index[N_updates] | inout | Array containing the positions of the split updates for later |
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| uint64_t | later | inout | Number of split updates for later |
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*** Requirements
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- ~Dim >= 2~
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- ~N_updates >= 1~
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- ~Updates~ is allocated with at least $1 \times 2 \times 8$ bytes
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- ~Updates_index~ is allocated with at least $1 \times 8$ bytes
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- ~breakdown~ is a small number such that $0 < breakdown << 1$
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- ~Slater_inv~ is allocated with at least $Dim \times Dim \times 8$ bytes
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- ~later_updates~ is allocated with at least $1 \times 2 \times 8$ bytes
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- ~later_index~ is allocated with at least $1 \times 8$ bytes
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- ~later >= 0~
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*** C header
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#+CALL: generate_c_header(table=qmckl_slagel_splitting_args,rettyp=get_value("CRetType"),fname=get_value("Name"))
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#+RESULTS:
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#+begin_src c :tangle (eval h_func) :comments org
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qmckl_exit_code qmckl_slagel_splitting_c (
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const uint64_t Dim,
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const uint64_t N_updates,
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const double* Updates,
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const uint64_t* Updates_index,
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const double breakdown,
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double* Slater_inv,
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double* later_updates,
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uint64_t* later_index,
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uint64_t* later );
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#+end_src
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*** Source Fortran
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*** Source C
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#+begin_src c :tangle (eval c) :comments org
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#include <stdbool.h>
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#include <math.h>
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#include "qmckl.h"
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qmckl_exit_code qmckl_slagel_splitting_c(uint64_t Dim,
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uint64_t N_updates,
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const double *Updates,
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const uint64_t *Updates_index,
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const double breakdown,
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double *Slater_inv,
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double *later_updates,
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uint64_t *later_index,
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uint64_t *later) {
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// #ifdef DEBUG // Leave commented out since debugging information is not yet implemented in QMCkl.
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// std::cerr << "Called slagel_splitting with " << N_updates << " updates" << std::endl;
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// #endif
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double C[Dim];
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double D[Dim];
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uint64_t l = 0;
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// For each update
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while (l < N_updates) {
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// C = S^{-1} x U_l
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for (uint64_t i = 0; i < Dim; i++) {
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C[i] = 0;
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for (uint64_t j = 0; j < Dim; j++) {
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C[i] += Slater_inv[i * Dim + j] * Updates[l * Dim + j];
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}
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}
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// Denominator
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double den = 1 + C[Updates_index[l] - 1];
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if (fabs(den) < breakdown) {
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// U_l = U_l / 2 (do the split)
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for (uint64_t i = 0; i < Dim; i++) {
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later_updates[*later * Dim + i] = Updates[l * Dim + i] / 2.0;
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C[i] /= 2.0;
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}
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later_index[*later] = Updates_index[l];
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(*later)++;
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den = 1 + C[Updates_index[l] - 1];
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}
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double iden = 1 / den;
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// D = v^T x S^{-1}
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for (uint64_t j = 0; j < Dim; j++) {
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D[j] = Slater_inv[(Updates_index[l] - 1) * Dim + j];
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}
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// S^{-1} = S^{-1} - C x D / den
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for (uint64_t i = 0; i < Dim; i++) {
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for (uint64_t j = 0; j < Dim; j++) {
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double update = C[i] * D[j] * iden;
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Slater_inv[i * Dim + j] -= update;
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}
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}
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l += 1;
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}
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return QMCKL_SUCCESS;
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}
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#+end_src
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*** Performance
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This function performce better for cycles with 1 rank-1 update and with a high fail-rate.
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** C interface :noexport:
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#+CALL: generate_c_interface(table=qmckl_slagel_splitting_args,rettyp=get_value("FRetType"),fname=get_value("Name"))
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#+RESULTS:
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#+begin_src f90 :tangle (eval f) :comments org :exports none
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integer(c_int32_t) function qmckl_slagel_splitting &
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(Dim, N_updates, Updates, Updates_index, breakdown, Slater_inv, later_updates, later_index, later) &
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bind(C) result(info)
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use, intrinsic :: iso_c_binding
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implicit none
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integer (c_int64_t) , intent(in) , value :: Dim
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integer (c_int64_t) , intent(in) , value :: N_updates
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real (c_double ) , intent(in) :: Updates(N_updates*Dim)
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integer (c_int64_t) , intent(in) :: Updates_index(N_updates)
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real (c_double ) , intent(in) , value :: breakdown
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real (c_double ) , intent(inout) :: Slater_inv(Dim*Dim)
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real (c_double ) , intent(inout) :: later_updates(Dim * N_updates)
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integer (c_int64_t) , intent(inout) :: later_index(N_updates)
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integer (c_int64_t) , intent(inout) :: later
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integer(c_int32_t), external :: qmckl_slagel_splitting_c
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info = qmckl_slagel_splitting_c &
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(Dim, N_updates, Updates, Updates_index, breakdown, Slater_inv, later_updates, later_index, later)
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end function qmckl_slagel_splitting
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#+end_src
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*** Test :noexport:
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This kernel does not have an explicit test because it is only used internally by higher-level Sherman-Morrison-Woodbury kernels.
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* End of files
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#+begin_src c :comments link :tangle (eval c_test)
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