From 8fe30673017e2b23c630c2f6e0575c6df98f3773 Mon Sep 17 00:00:00 2001
From: Ping-Hsuan <pht2@illinois.edu>
Date: Mon, 21 Oct 2024 16:18:55 -0500
Subject: [PATCH] support EFR-ROM in NekROM

---
 code/MOR      |  1 +
 code/MORDICT  | 31 ++++++++++++++++---------------
 code/filter.f | 22 ++++++++++++++++++++++
 code/mpar.f   |  4 ++++
 code/time.f   | 21 ++++++++++++++-------
 5 files changed, 57 insertions(+), 22 deletions(-)

diff --git a/code/MOR b/code/MOR
index 5362560c..c7a9cbac 100644
--- a/code/MOR
+++ b/code/MOR
@@ -219,6 +219,7 @@ c     parameters and common blocks for MOR
       integer rbf 
       common /morfilter/ rdft,dfops(lub*lub)
       common /morifilt/  rbf
+      common /morrelax/  relax
 
       ! Tensor Decomposition 
 
diff --git a/code/MORDICT b/code/MORDICT
index 342b1967..81e66da6 100644
--- a/code/MORDICT
+++ b/code/MORDICT
@@ -4,7 +4,7 @@ c     Note: Keys have to be in capital letters
 c
       integer MORDICT_NKEYS
 
-      parameter (MORDICT_NKEYS = 61)
+      parameter (MORDICT_NKEYS = 62)
 
       character*132 mordictkey(MORDICT_NKEYS)
       data
@@ -55,17 +55,18 @@ c
      &  mordictkey(45) / 'FILTER:TYPE' /
      &  mordictkey(46) / 'FILTER:MODES' /
      &  mordictkey(47) / 'FILTER:RADIUS' /
-     &  mordictkey(48) / 'BUOYANCY' /
-     &  mordictkey(49) / 'BUOYANCY:MAGNITUDE' /
-     &  mordictkey(50) / 'BUOYANCY:ANGLE' /
-     &  mordictkey(51) / 'BUOYANCY:GX' /
-     &  mordictkey(52) / 'BUOYANCY:GY' /
-     &  mordictkey(53) / 'BUOYANCY:GZ' /
-     &  mordictkey(54) / 'EI' /
-     &  mordictkey(55) / 'EI:MODE' /
-     &  mordictkey(56) / 'EI:EQN' /
-     &  mordictkey(57) / 'TENDEC' /
-     &  mordictkey(58) / 'TENDEC:MODE' /
-     &  mordictkey(59) / 'TENDEC:RANK' /
-     &  mordictkey(60) / 'TENDEC:CORE' /
-     &  mordictkey(61) / 'TENDEC:SKEW' /
+     &  mordictkey(48) / 'FILTER:RELAXATION' /
+     &  mordictkey(49) / 'BUOYANCY' /
+     &  mordictkey(50) / 'BUOYANCY:MAGNITUDE' /
+     &  mordictkey(51) / 'BUOYANCY:ANGLE' /
+     &  mordictkey(52) / 'BUOYANCY:GX' /
+     &  mordictkey(53) / 'BUOYANCY:GY' /
+     &  mordictkey(54) / 'BUOYANCY:GZ' /
+     &  mordictkey(55) / 'EI' /
+     &  mordictkey(56) / 'EI:MODE' /
+     &  mordictkey(57) / 'EI:EQN' /
+     &  mordictkey(58) / 'TENDEC' /
+     &  mordictkey(59) / 'TENDEC:MODE' /
+     &  mordictkey(60) / 'TENDEC:RANK' /
+     &  mordictkey(61) / 'TENDEC:CORE' /
+     &  mordictkey(62) / 'TENDEC:SKEW' /
diff --git a/code/filter.f b/code/filter.f
index 49a9728c..9bbe8d76 100644
--- a/code/filter.f
+++ b/code/filter.f
@@ -245,3 +245,25 @@ subroutine evalnut(nut,u1,u2,u3)
       return
       end
 c-----------------------------------------------------------------------
+      subroutine efr_relaxation(filtered_coef,coef,relax,nb)
+
+      ! perform the relaxation step in the evolve-filter-relaxation method
+
+      ! INPUT:
+      ! filtered_coef := filtered ROM coefficient
+      ! coef          := ROM coefficient
+      ! relax         := relaxation parameter ([0, 1])
+      ! nb            := size of filtered_coef and coef arrays
+
+      ! OUTPUT:
+      ! filtered_coef := (1-relax)*coef + relax*filtered_coef
+
+      real filtered_coef(1:nb), coef(1:nb)
+      real relax
+      integer nb
+
+      call cmult(filtered_coef,relax,nb)
+      call add2s2(filtered_coef,coef,(1.-relax),nb)
+
+      return
+      end
diff --git a/code/mpar.f b/code/mpar.f
index 38c4a394..3c173fdf 100644
--- a/code/mpar.f
+++ b/code/mpar.f
@@ -411,6 +411,9 @@ subroutine mpar_read(ierr)
          endif
       endif
 
+      call finiparser_getdbl(d_out,'filter:relaxation',ifnd)
+      if (ifnd.eq.1) relax=d_out
+
       ! EI
 
       call finiparser_getbool(i_out,'ei:mode',ifnd)
@@ -547,6 +550,7 @@ subroutine bcastmpar
       call bcast(tbarr0,wdsize)
       call bcast(rbf,wdsize)
       call bcast(rdft,wdsize)
+      call bcast(relax,wdsize)
       call bcast(gx,wdsize)
       call bcast(gy,wdsize)
       call bcast(gz,wdsize)
diff --git a/code/time.f b/code/time.f
index 265402c3..7cebe5c7 100644
--- a/code/time.f
+++ b/code/time.f
@@ -198,11 +198,13 @@ subroutine bdfext_step
          endif
 
          if (cfloc.eq.'POST') then
-         if (cftype.eq.'TFUN') then
-            call pod_proj(rhs(1,1),rbf,nb,'step  ')
-         else if (cftype.eq.'DIFF') then
-            call pod_df(rhs(1,1))
-         endif
+            ! copy unfiltered coefficients
+            call copy(utmp1(1),rhs(1,1),nb)
+            if (cftype.eq.'TFUN') then
+               call pod_proj(rhs(1,1),rbf,nb,'step  ')
+            else if (cftype.eq.'DIFF') then
+               call pod_df(rhs(1,1))
+            endif
          endif
 
          solve_time=solve_time+dnekclock()-ttime
@@ -238,8 +240,13 @@ subroutine bdfext_step
          call copy(rhs(1,2),rhs(1,1),nb)
       endif
 
-      if (cfloc.eq.'POST'.and.cftype.eq.'POLY')
-     $   call apply_les_imp(rhs(0,1),rhs(0,2),rdft,fles1,fles2,rtmp1)
+      if (cfloc.eq.'POST') then
+         if (cftype.eq.'POLY') then
+            call apply_les_imp(rhs(0,1),rhs(0,2),rdft,fles1,fles2,rtmp1)
+         elseif ((cftype.eq.'TFUN').or.(cftype.eq.'DIFF')) then
+            call efr_relaxation(rhs(1,1),utmp1(1),relax,nb)
+         endif
+      endif
 
       if (ifrom(2)) call shift(ut,rhs(0,2),nb+1,5)
       if (ifrom(1)) call shift(u,rhs,nb+1,5)