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Update GaussFFT_2D_Fast.f90
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Yonfou authored Aug 12, 2024
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249 changes: 0 additions & 249 deletions GaussFFT_2D_Fast.f90
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!Copyright (c) 2022 Fang Ouyang and Longwei Chen All rights reserved.
!
!Redistribution and use in source and binary forms, with or without
!modification, are permitted provided that the following conditions are met:
!
!1. Redistributions of source code must retain the above copyright notice, this
! list of conditions and the following disclaimer.
!
!2. Redistributions in binary form must reproduce the above copyright notice,
! this list of conditions and the following disclaimer in the documentation
! and/or other materials provided with the distribution.
!
!3. Neither the name of the copyright holder nor the names of its
! contributors may be used to endorse or promote products derived from
! this software without specific prior written permission.
!
!THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
!AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
!IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
!DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
!FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
!DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
!SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
!CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
!OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
!OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

SUBROUTINE GaussFFT_2D_Fast(NX,NY,DX,DY,NG,AP,TP,X,Y,OFST,FI,FO,SIGN)
!--------------------------------------------------------------------------------------------------

IMPLICIT NONE

INTEGER(KIND=4)::NX,NY,NG,SIGN
REAL (KIND=8)::DX,DY,X(NX),Y(NY),AP(NG),TP(NG)
COMPLEX(KIND=8)::FI(NX,NY),FO(NG,NG,NX,NY),OFST(NG,NG,NX,NY)

INTEGER(KIND=4)::I,J
REAL (KIND=8)::PI,CC
COMPLEX(KIND=8)::CP_I

!--------------------------------------------------------------------------------------------------



PI=3.14159265358979323846
CP_I=(0.,1.)


IF(SIGN==1) THEN

FO(:,:,:,:)=0.

CC=DX*DY

DO I=1,NG
DO J=1,NG

FO(I,J,:,:)=FI*OFST(I,J,:,:)*CC

CALL FFT_2D(NX,NY,FO(I,J,:,:),1)

END DO
END DO


END IF


IF(SIGN==-1) THEN

FI(:,:)=0.

CC=NX*NY*DX*DY

DO I=1,NG
DO J=1,NG


CALL FFT_2D(NX,NY,FO(I,J,:,:),-1)

FI=FI+FO(I,J,:,:)/OFST(I,J,:,:)*AP(I)*AP(J)/CC

END DO
END DO


END IF


!--------------------------------------------------------------------------------------------------
RETURN
END SUBROUTINE
!--------------------------------------------------------------------------------------------------




SUBROUTINE GaussPoint(N_Guass,AP,TP)
!--------------------------------------------------------------------------------------------------
IMPLICIT NONE

INTEGER(KIND=4)::N_Guass
REAL (KIND=8)::AP(N_Guass),TP(N_Guass)
!--------------------------------------------------------------------------------------------------

AP(:)=0.; TP(:)=0.


IF(N_Guass==1) THEN

TP(1) = 0.

AP(1) = 1.

ELSE IF(N_Guass==2) THEN

TP(1) = (3.-sqrt(3.))/6.
TP(2) = (3.+sqrt(3.))/6.

AP(1) = 0.5
AP(2) = 0.5

ELSE IF(N_Guass==3) THEN

TP(1) = (5.-sqrt(15.))/10.
TP(2) = 0.5
TP(3) = (5.+sqrt(15.))/10.

AP(1) = 5./18.
AP(2) = 4./9.
AP(3) = 5./18.

ELSE IF(N_Guass==4) THEN

TP(1) = 0.069431844202974
TP(2) = 0.330009478207572
TP(3) = 0.669990521792428
TP(4) = 0.930568155797026

AP(1) = 0.173927422568727
AP(2) = 0.326072577431273
AP(3) = 0.326072577431273
AP(4) = 0.173927422568727

END IF


!--------------------------------------------------------------------------------------------------
RETURN
END SUBROUTINE
!--------------------------------------------------------------------------------------------------





SUBROUTINE WaveNumberSequence(M,P)
!--------------------------------------------------------------------------------------------------
IMPLICIT NONE

INTEGER(KIND=4)::M,I
INTEGER(KIND=4)::P(M)
!--------------------------------------------------------------------------------------------------

P(:)=0.


IF(MOD(M,2)==0) THEN

P(1)=0
P(M/2+1)=-M/2

DO I=1,M/2-1

P(I+1)=I
P(M-I+1)=-I

END DO

ELSE

P(1)=0

DO I=1,(M-1)/2

P(I+1)=I
P(M-I+1)=-I

END DO

END IF


!--------------------------------------------------------------------------------------------------
RETURN
END SUBROUTINE
!--------------------------------------------------------------------------------------------------





SUBROUTINE FFT_2D(NX,NY,F,SIGN)
!--------------------------------------------------------------------------------------------------
IMPLICIT NONE

INCLUDE 'FFTW3.F'

INTEGER(KIND=4)::SIGN,NX,NY
COMPLEX(KIND=8)::F(NX,NY)
COMPLEX(KIND=8),ALLOCATABLE::FO(:,:)
INTEGER(KIND=8)::FWD,BWD,STATUS
!--------------------------------------------------------------------------------------------------

ALLOCATE(FO(NX,NY)); FO(:,:)=0.

IF(SIGN==1) THEN

FWD=0; STATUS=0

CALL DFFTW_PLAN_DFT_2D(FWD,NX,NY,F,FO,FFTW_FORWARD,FFTW_ESTIMATE)

CALL DFFTW_EXECUTE(FWD,F,FO)

CALL DFFTW_DESTROY_PLAN(FWD)

F(:,:)=FO(:,:)

END IF

IF(SIGN==-1) THEN

BWD=0; STATUS=0

CALL DFFTW_PLAN_DFT_2D(BWD,NX,NY,F,FO,FFTW_BACKWARD,FFTW_ESTIMATE)

CALL DFFTW_EXECUTE_DFT(BWD,F,FO)

CALL DFFTW_DESTROY_PLAN(BWD)

F(:,:)=FO(:,:)

END IF


DEALLOCATE(FO)
!--------------------------------------------------------------------------------------------------
RETURN
END SUBROUTINE
!--------------------------------------------------------------------------------------------------

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