!> @file singleton_mod.f90 !------------------------------------------------------------------------------! ! Current revisions: ! ----------------- ! ! ! Former revisions: ! ----------------- ! $Id: singleton_mod.f90 2001 2016-08-20 18:41:22Z kanani $ ! ! 2000 2016-08-20 18:09:15Z knoop ! Forced header and separation lines into 80 columns ! ! 1850 2016-04-08 13:29:27Z maronga ! Module renamed ! ! ! 1682 2015-10-07 23:56:08Z knoop ! Code annotations made doxygen readable ! ! 1320 2014-03-20 08:40:49Z raasch ! kind-parameters added to all INTEGER and REAL declaration statements, ! kinds are defined in new module kinds, ! revision history before 2012 removed, ! ! Revision 1.1 2002/05/02 18:56:59 raasch ! Initial revision ! ! ! Description: ! ------------ !> Multivariate Fast Fourier Transform !> !> Fortran 90 Implementation of Singleton's mixed-radix algorithm, !> RC Singleton, Stanford Research Institute, Sept. 1968. !> !> Adapted from fftn.c, translated from Fortran 66 to C by Mark Olesen and !> John Beale. !> !> Fourier transforms can be computed either in place, using assumed size !> arguments, or by generic function, using assumed shape arguments. !> !> !> Public: !> !> fftkind kind parameter of complex arguments !> and function results. !> !> fft(array, dim, inv, stat) generic transform function !> COMPLEX(fftkind), DIMENSION(:,...,:), INTENT(IN) :: array !> INTEGER, DIMENSION(:), INTENT(IN), OPTIONAL:: dim !> LOGICAL, INTENT(IN), OPTIONAL:: inv !> INTEGER, INTENT(OUT), OPTIONAL:: stat !> !> fftn(array, shape, dim, inv, stat) in place transform subroutine !> COMPLEX(fftkind), DIMENSION(*), INTENT(INOUT) :: array !> INTEGER, DIMENSION(:), INTENT(IN) :: shape !> INTEGER, DIMENSION(:), INTENT(IN), OPTIONAL:: dim !> LOGICAL, INTENT(IN), OPTIONAL:: inv !> INTEGER, INTENT(OUT), OPTIONAL:: stat !> !> !> Formal Parameters: !> !> array The complex array to be transformed. array can be of arbitrary !> rank (i.e. up to seven). !> !> shape With subroutine fftn, the shape of the array to be transformed !> has to be passed separately, since fftradix - the internal trans- !> formation routine - will treat array always as one dimensional. !> The product of elements in shape must be the number of !> elements in array. !> Although passing array with assumed shape would have been nicer, !> I prefered assumed size in order to prevent the compiler from !> using a copy-in-copy-out mechanism. That would generally be !> necessary with fftn passing array to fftradix and with fftn !> being prepared for accepting non consecutive array sections. !> Using assumed size, it's up to the user to pass an array argu- !> ment, that can be addressed as continous one dimensional array !> without copying. Otherwise, transformation will not really be !> performed in place. !> On the other hand, since the rank of array and the size of !> shape needn't match, fftn is appropriate for handling more than !> seven dimensions. !> As far as function fft is concerned all this doesn't matter, !> because the argument will be copied anyway. Thus no extra !> shape argument is needed for fft. !> !> Optional Parameters: !> !> dim One dimensional integer array, containing the dimensions to be !> transformed. Default is (/1,...,N/) with N being the rank of !> array, i.e. complete transform. dim can restrict transformation !> to a subset of available dimensions. Its size must not exceed the !> rank of array or the size of shape respectivly. !> !> inv If .true., inverse transformation will be performed. Default is !> .false., i.e. forward transformation. !> !> stat If present, a system dependent nonzero status value will be !> returned in stat, if allocation of temporary storage failed. !> !> !> Scaling: !> !> Transformation results will always be scaled by the square root of the !> product of sizes of each dimension in dim. (See examples below) !> !> !> Examples: !> !> Let A be a L*M*N three dimensional complex array. Then !> !> result = fft(A) !> !> will produce a three dimensional transform, scaled by sqrt(L*M*N), while !> !> call fftn(A, SHAPE(A)) !> !> will do the same in place. !> !> result = fft(A, dim=(/1,3/)) !> !> will transform with respect to the first and the third dimension, scaled !> by sqrt(L*N). !> !> result = fft(fft(A), inv=.true.) !> !> should (approximately) reproduce A. !> With B having the same shape as A !> !> result = fft(fft(A) * CONJG(fft(B)), inv=.true.) !> !> will correlate A and B. !> !> !> Remarks: !> !> Following changes have been introduced with respect to fftn.c: !> - complex arguments and results are of type complex, rather than !> real an imaginary part separately. !> - increment parameter (magnitude of isign) has been dropped, !> inc is always one, direction of transform is given by inv. !> - maxf and maxp have been dropped. The amount of temporary storage !> needed is determined by the fftradix routine. Both fftn and fft !> can handle any size of array. (Maybe they take a lot of time and !> memory, but they will do it) !> !> Redesigning fftradix in a way, that it handles assumed shape arrays !> would have been desirable. However, I found it rather hard to do this !> in an efficient way. Problems were: !> - to prevent stride multiplications when indexing arrays. At least our !> compiler was not clever enough to discover that in fact additions !> would do the job as well. On the other hand, I haven't been clever !> enough to find an implementation using array operations. !> - fftradix is rather large and different versions would be necessaray !> for each possible rank of array. !> Consequently, in place transformation still needs the argument stored !> in a consecutive bunch of memory and can't be performed on array !> sections like A(100:199:-3, 50:1020). Calling fftn with such sections !> will most probably imply copy-in-copy-out. However, the function fft !> works with everything it gets and should be convenient to use. !> !> Michael Steffens, 09.12.96, !> Restructured fftradix for better optimization. M. Steffens, 4 June 1997 !------------------------------------------------------------------------------! MODULE singleton USE kinds IMPLICIT NONE PRIVATE PUBLIC:: fft, fftn REAL(wp), PARAMETER:: sin60 = 0.86602540378443865_wp REAL(wp), PARAMETER:: cos72 = 0.30901699437494742_wp REAL(wp), PARAMETER:: sin72 = 0.95105651629515357_wp REAL(wp), PARAMETER:: pi = 3.14159265358979323_wp INTERFACE fft MODULE PROCEDURE fft1d MODULE PROCEDURE fft2d MODULE PROCEDURE fft3d MODULE PROCEDURE fft4d MODULE PROCEDURE fft5d MODULE PROCEDURE fft6d MODULE PROCEDURE fft7d END INTERFACE CONTAINS !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft1d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION(SIZE(array, 1)):: ft INTEGER(iwp):: ishape(1) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, inv = inv, stat = stat) END FUNCTION fft1d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft2d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION(SIZE(array, 1), SIZE(array, 2)):: ft INTEGER(iwp) :: ishape(2) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft2d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft3d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), & DIMENSION(SIZE(array, 1), SIZE(array, 2), SIZE(array, 3)):: ft INTEGER(iwp) :: ishape(3) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft3d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft4d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:,:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION( & SIZE(array, 1), SIZE(array, 2), SIZE(array, 3), SIZE(array, 4)):: ft INTEGER(iwp) :: ishape(4) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft4d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft5d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:,:,:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION( & SIZE(array, 1), SIZE(array, 2), SIZE(array, 3), SIZE(array, 4), & SIZE(array, 5)):: ft INTEGER(iwp) :: ishape(5) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft5d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft6d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:,:,:,:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION( & SIZE(array, 1), SIZE(array, 2), SIZE(array, 3), SIZE(array, 4), & SIZE(array, 5), SIZE(array, 6)):: ft INTEGER(iwp) :: ishape(6) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft6d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing function description. !------------------------------------------------------------------------------! FUNCTION fft7d(array, dim, inv, stat) RESULT(ft) ! !-- Formal parameters COMPLEX(wp), DIMENSION(:,:,:,:,:,:,:), INTENT(IN) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Function result COMPLEX(wp), DIMENSION( & SIZE(array, 1), SIZE(array, 2), SIZE(array, 3), SIZE(array, 4), & SIZE(array, 5), SIZE(array, 6), SIZE(array, 7)):: ft INTEGER(iwp) :: ishape(7) ! !-- Intrinsics used INTRINSIC SIZE, SHAPE ft = array ishape = SHAPE( array ) CALL fftn(ft, ishape, dim, inv, stat) END FUNCTION fft7d !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing subroutine description. !------------------------------------------------------------------------------! SUBROUTINE fftn(array, shape, dim, inv, stat) ! !-- Formal parameters COMPLEX(wp), DIMENSION(*), INTENT(INOUT) :: array INTEGER(iwp), DIMENSION(:), INTENT(IN) :: shape INTEGER(iwp), DIMENSION(:), INTENT(IN), OPTIONAL:: dim INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN), OPTIONAL:: inv ! !-- Local arrays INTEGER(iwp), DIMENSION(SIZE(shape)):: d ! !-- Local scalars LOGICAL :: inverse INTEGER(iwp) :: i, ndim, ntotal REAL(wp):: scale ! !-- Intrinsics used INTRINSIC PRESENT, MIN, PRODUCT, SIZE, SQRT ! !-- Optional parameter settings IF (PRESENT(inv)) THEN inverse = inv ELSE inverse = .FALSE. END IF IF (PRESENT(dim)) THEN ndim = MIN(SIZE(dim), SIZE(d)) d(1:ndim) = DIM(1:ndim) ELSE ndim = SIZE(d) d = (/(i, i = 1, SIZE(d))/) END IF ntotal = PRODUCT(shape) scale = SQRT(1.0_wp / PRODUCT(shape(d(1:ndim)))) DO i = 1, ntotal array(i) = CMPLX(REAL(array(i)) * scale, AIMAG(array(i)) * scale, & KIND=wp) END DO DO i = 1, ndim CALL fftradix(array, ntotal, shape(d(i)), PRODUCT(shape(1:d(i))), & inverse, stat) IF (PRESENT(stat)) THEN IF (stat /=0) RETURN END IF END DO END SUBROUTINE fftn !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing subroutine description. !------------------------------------------------------------------------------! SUBROUTINE fftradix(array, ntotal, npass, nspan, inv, stat) ! !-- Formal parameters COMPLEX(wp), DIMENSION(*), INTENT(INOUT) :: array INTEGER(iwp), INTENT(IN) :: ntotal, npass, nspan INTEGER(iwp), INTENT(OUT), OPTIONAL:: stat LOGICAL, INTENT(IN) :: inv ! !-- Local arrays COMPLEX(wp), DIMENSION(:), ALLOCATABLE :: ctmp INTEGER(iwp), DIMENSION(BIT_SIZE(0)) :: factor INTEGER(iwp), DIMENSION(:), ALLOCATABLE :: perm REAL(wp), DIMENSION(:), ALLOCATABLE :: sine, cosine ! !-- Local scalars INTEGER(iwp) :: maxfactor, nfactor, nsquare, nperm ! !-- Intrinsics used INTRINSIC MAXVAL, MOD, PRESENT, ISHFT, BIT_SIZE, SIN, COS, & CMPLX, REAL, AIMAG IF (npass <= 1) RETURN CALL factorize(npass, factor, nfactor, nsquare) maxfactor = MAXVAL(factor(:nfactor)) IF (nfactor - ISHFT(nsquare, 1) > 0) THEN nperm = MAX(nfactor + 1, PRODUCT(factor(nsquare+1: nfactor-nsquare)) - 1) ELSE nperm = nfactor + 1 END IF IF (PRESENT(stat)) THEN ALLOCATE(ctmp(maxfactor), sine(maxfactor), cosine(maxfactor), STAT=stat) IF (stat /= 0) RETURN CALL transform(array, ntotal, npass, nspan, & factor, nfactor, ctmp, sine, cosine, inv) DEALLOCATE(sine, cosine, STAT=stat) IF (stat /= 0) RETURN ALLOCATE(perm(nperm), STAT=stat) IF (stat /= 0) RETURN CALL permute(array, ntotal, npass, nspan, & factor, nfactor, nsquare, maxfactor, & ctmp, perm) DEALLOCATE(perm, ctmp, STAT=stat) IF (stat /= 0) RETURN ELSE ALLOCATE(ctmp(maxfactor), sine(maxfactor), cosine(maxfactor)) CALL transform(array, ntotal, npass, nspan, & factor, nfactor, ctmp, sine, cosine, inv) DEALLOCATE(sine, cosine) ALLOCATE(perm(nperm)) CALL permute(array, ntotal, npass, nspan, & factor, nfactor, nsquare, maxfactor, & ctmp, perm) DEALLOCATE(perm, ctmp) END IF CONTAINS !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing subroutine description. !------------------------------------------------------------------------------! SUBROUTINE factorize(npass, factor, nfactor, nsquare) ! !-- Formal parameters INTEGER(iwp), INTENT(IN) :: npass INTEGER(iwp), DIMENSION(*), INTENT(OUT):: factor INTEGER(iwp), INTENT(OUT):: nfactor, nsquare ! !-- Local scalars INTEGER(iwp):: j, jj, k nfactor = 0 k = npass DO WHILE (MOD(k, 16) == 0) nfactor = nfactor + 1 factor(nfactor) = 4 k = k / 16 END DO j = 3 jj = 9 DO DO WHILE (MOD(k, jj) == 0) nfactor = nfactor + 1 factor(nfactor) = j k = k / jj END DO j = j + 2 jj = j * j IF (jj > k) EXIT END DO IF (k <= 4) THEN nsquare = nfactor factor(nfactor + 1) = k IF (k /= 1) nfactor = nfactor + 1 ELSE IF (k - ISHFT(k / 4, 2) == 0) THEN nfactor = nfactor + 1 factor(nfactor) = 2 k = k / 4 END IF nsquare = nfactor j = 2 DO IF (MOD(k, j) == 0) THEN nfactor = nfactor + 1 factor(nfactor) = j k = k / j END IF j = ISHFT((j + 1) / 2, 1) + 1 IF (j > k) EXIT END DO END IF IF (nsquare > 0) THEN j = nsquare DO nfactor = nfactor + 1 factor(nfactor) = factor(j) j = j - 1 IF (j==0) EXIT END DO END IF END SUBROUTINE factorize !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing subroutine description. !------------------------------------------------------------------------------! SUBROUTINE transform(array, ntotal, npass, nspan, & factor, nfactor, ctmp, sine, cosine, inv) !-- compute fourier transform ! !-- Formal parameters COMPLEX(wp), DIMENSION(*), INTENT(IN OUT):: array COMPLEX(wp), DIMENSION(*), INTENT(OUT) :: ctmp INTEGER(iwp), INTENT(IN) :: ntotal, npass, nspan INTEGER(iwp), DIMENSION(*), INTENT(IN) :: factor INTEGER(iwp), INTENT(IN) :: nfactor LOGICAL, INTENT(IN) :: inv REAL(wp), DIMENSION(*), INTENT(OUT) :: sine, cosine ! !-- Local scalars INTEGER(iwp):: ii, ispan INTEGER(iwp):: j, jc, jf, jj INTEGER(iwp):: k, kk, kspan, k1, k2, k3, k4 INTEGER(iwp):: nn, nt REAL(wp) :: s60, c72, s72, pi2, radf REAL(wp) :: c1, s1, c2, s2, c3, s3, cd, sd, ak COMPLEX(wp) :: cc, cj, ck, cjp, cjm, ckp, ckm c72 = cos72 IF (inv) THEN s72 = sin72 s60 = sin60 pi2 = pi ELSE s72 = -sin72 s60 = -sin60 pi2 = -pi END IF nt = ntotal nn = nt - 1 kspan = nspan jc = nspan / npass radf = pi2 * jc pi2 = pi2 * 2.0_wp !-- use 2 PI from here on ii = 0 jf = 0 DO sd = radf / kspan cd = SIN(sd) cd = 2.0_wp * cd * cd sd = SIN(sd + sd) kk = 1 ii = ii + 1 SELECT CASE (factor(ii)) CASE (2) ! !-- Transform for factor of 2 (including rotation factor) kspan = kspan / 2 k1 = kspan + 2 DO DO k2 = kk + kspan ck = array(k2) array(k2) = array(kk)-ck array(kk) = array(kk) + ck kk = k2 + kspan IF (kk > nn) EXIT END DO kk = kk - nn IF (kk > jc) EXIT END DO IF (kk > kspan) RETURN DO c1 = 1.0_wp - cd s1 = sd DO DO DO k2 = kk + kspan ck = array(kk) - array(k2) array(kk) = array(kk) + array(k2) array(k2) = ck * CMPLX(c1, s1, KIND=wp) kk = k2 + kspan IF (kk >= nt) EXIT END DO k2 = kk - nt c1 = -c1 kk = k1 - k2 IF (kk <= k2) EXIT END DO ak = c1 - (cd * c1 + sd * s1) s1 = sd * c1 - cd * s1 + s1 c1 = 2.0_wp - (ak * ak + s1 * s1) s1 = s1 * c1 c1 = c1 * ak kk = kk + jc IF (kk >= k2) EXIT END DO k1 = k1 + 1 + 1 kk = (k1 - kspan) / 2 + jc IF (kk > jc + jc) EXIT END DO CASE (4) !-- transform for factor of 4 ispan = kspan kspan = kspan / 4 DO c1 = 1.0_wp s1 = 0.0_wp DO DO k1 = kk + kspan k2 = k1 + kspan k3 = k2 + kspan ckp = array(kk) + array(k2) ckm = array(kk) - array(k2) cjp = array(k1) + array(k3) cjm = array(k1) - array(k3) array(kk) = ckp + cjp cjp = ckp - cjp IF (inv) THEN ckp = ckm + CMPLX(-AIMAG(cjm), REAL(cjm), KIND=wp) ckm = ckm + CMPLX(AIMAG(cjm), -REAL(cjm), KIND=wp) ELSE ckp = ckm + CMPLX(AIMAG(cjm), -REAL(cjm), KIND=wp) ckm = ckm + CMPLX(-AIMAG(cjm), REAL(cjm), KIND=wp) END IF ! !-- Avoid useless multiplies IF (s1 == 0.0_wp) THEN array(k1) = ckp array(k2) = cjp array(k3) = ckm ELSE array(k1) = ckp * CMPLX(c1, s1, KIND=wp) array(k2) = cjp * CMPLX(c2, s2, KIND=wp) array(k3) = ckm * CMPLX(c3, s3, KIND=wp) END IF kk = k3 + kspan IF (kk > nt) EXIT END DO c2 = c1 - (cd * c1 + sd * s1) s1 = sd * c1 - cd * s1 + s1 c1 = 2.0_wp - (c2 * c2 + s1 * s1) s1 = s1 * c1 c1 = c1 * c2 ! !-- Values of c2, c3, s2, s3 that will get used next time c2 = c1 * c1 - s1 * s1 s2 = 2.0_wp * c1 * s1 c3 = c2 * c1 - s2 * s1 s3 = c2 * s1 + s2 * c1 kk = kk - nt + jc IF (kk > kspan) EXIT END DO kk = kk - kspan + 1 IF (kk > jc) EXIT END DO IF (kspan == jc) RETURN CASE default ! !-- Transform for odd factors k = factor(ii) ispan = kspan kspan = kspan / k SELECT CASE (k) CASE (3) !-- transform for factor of 3 (optional code) DO DO k1 = kk + kspan k2 = k1 + kspan ck = array(kk) cj = array(k1) + array(k2) array(kk) = ck + cj ck = ck - CMPLX( & 0.5_wp * REAL (cj), & 0.5_wp * AIMAG(cj), & KIND=wp) cj = CMPLX( & (REAL (array(k1)) - REAL (array(k2))) * s60, & (AIMAG(array(k1)) - AIMAG(array(k2))) * s60, & KIND=wp) array(k1) = ck + CMPLX(-AIMAG(cj), REAL(cj), KIND=wp) array(k2) = ck + CMPLX(AIMAG(cj), -REAL(cj), KIND=wp) kk = k2 + kspan IF (kk >= nn) EXIT END DO kk = kk - nn IF (kk > kspan) EXIT END DO CASE (5) !-- transform for factor of 5 (optional code) c2 = c72 * c72 - s72 * s72 s2 = 2.0_wp * c72 * s72 DO DO k1 = kk + kspan k2 = k1 + kspan k3 = k2 + kspan k4 = k3 + kspan ckp = array(k1) + array(k4) ckm = array(k1) - array(k4) cjp = array(k2) + array(k3) cjm = array(k2) - array(k3) cc = array(kk) array(kk) = cc + ckp + cjp ck = CMPLX(REAL(ckp) * c72, AIMAG(ckp) * c72, & KIND=wp) + & CMPLX(REAL(cjp) * c2, AIMAG(cjp) * c2, & KIND=wp) + cc cj = CMPLX(REAL(ckm) * s72, AIMAG(ckm) * s72, & KIND=wp) + & CMPLX(REAL(cjm) * s2, AIMAG(cjm) * s2, & KIND=wp) array(k1) = ck + CMPLX(-AIMAG(cj), REAL(cj), KIND=wp) array(k4) = ck + CMPLX(AIMAG(cj), -REAL(cj), KIND=wp) ck = CMPLX(REAL(ckp) * c2, AIMAG(ckp) * c2, & KIND=wp) + & CMPLX(REAL(cjp) * c72, AIMAG(cjp) * c72, & KIND=wp) + cc cj = CMPLX(REAL(ckm) * s2, AIMAG(ckm) * s2, & KIND=wp) - & CMPLX(REAL(cjm) * s72, AIMAG(cjm) * s72, & KIND=wp) array(k2) = ck + CMPLX(-AIMAG(cj), REAL(cj), KIND=wp) array(k3) = ck + CMPLX(AIMAG(cj), -REAL(cj), KIND=wp) kk = k4 + kspan IF (kk >= nn) EXIT END DO kk = kk - nn IF (kk > kspan) EXIT END DO CASE default IF (k /= jf) THEN jf = k s1 = pi2 / k c1 = COS(s1) s1 = SIN(s1) cosine (jf) = 1.0_wp sine (jf) = 0.0_wp j = 1 DO cosine (j) = cosine (k) * c1 + sine (k) * s1 sine (j) = cosine (k) * s1 - sine (k) * c1 k = k-1 cosine (k) = cosine (j) sine (k) = -sine (j) j = j + 1 IF (j >= k) EXIT END DO END IF DO DO k1 = kk k2 = kk + ispan cc = array(kk) ck = cc j = 1 k1 = k1 + kspan DO k2 = k2 - kspan j = j + 1 ctmp(j) = array(k1) + array(k2) ck = ck + ctmp(j) j = j + 1 ctmp(j) = array(k1) - array(k2) k1 = k1 + kspan IF (k1 >= k2) EXIT END DO array(kk) = ck k1 = kk k2 = kk + ispan j = 1 DO k1 = k1 + kspan k2 = k2 - kspan jj = j ck = cc cj = (0.0_wp, 0.0_wp) k = 1 DO k = k + 1 ck = ck + CMPLX( & REAL (ctmp(k)) * cosine(jj), & AIMAG(ctmp(k)) * cosine(jj), KIND=wp) k = k + 1 cj = cj + CMPLX( & REAL (ctmp(k)) * sine(jj), & AIMAG(ctmp(k)) * sine(jj), KIND=wp) jj = jj + j IF (jj > jf) jj = jj - jf IF (k >= jf) EXIT END DO k = jf - j array(k1) = ck + CMPLX(-AIMAG(cj), REAL(cj), & KIND=wp) array(k2) = ck + CMPLX(AIMAG(cj), -REAL(cj), & KIND=wp) j = j + 1 IF (j >= k) EXIT END DO kk = kk + ispan IF (kk > nn) EXIT END DO kk = kk - nn IF (kk > kspan) EXIT END DO END SELECT ! !-- Multiply by rotation factor (except for factors of 2 and 4) IF (ii == nfactor) RETURN kk = jc + 1 DO c2 = 1.0_wp - cd s1 = sd DO c1 = c2 s2 = s1 kk = kk + kspan DO DO array(kk) = CMPLX(c2, s2, KIND=wp) * array(kk) kk = kk + ispan IF (kk > nt) EXIT END DO ak = s1 * s2 s2 = s1 * c2 + c1 * s2 c2 = c1 * c2 - ak kk = kk - nt + kspan IF (kk > ispan) EXIT END DO c2 = c1 - (cd * c1 + sd * s1) s1 = s1 + sd * c1 - cd * s1 c1 = 2.0_wp - (c2 * c2 + s1 * s1) s1 = s1 * c1 c2 = c2 * c1 kk = kk - ispan + jc IF (kk > kspan) EXIT END DO kk = kk - kspan + jc + 1 IF (kk > jc + jc) EXIT END DO END SELECT END DO END SUBROUTINE transform !------------------------------------------------------------------------------! ! Description: ! ------------ !> @todo Missing subroutine description. !------------------------------------------------------------------------------! SUBROUTINE permute(array, ntotal, npass, nspan, & factor, nfactor, nsquare, maxfactor, & ctmp, perm) ! !-- Formal parameters COMPLEX(wp), DIMENSION(*), INTENT(IN OUT):: array COMPLEX(wp), DIMENSION(*), INTENT(OUT) :: ctmp INTEGER(iwp), INTENT(IN) :: ntotal, npass, nspan INTEGER(iwp), DIMENSION(*), INTENT(IN OUT):: factor INTEGER(iwp), INTENT(IN) :: nfactor, nsquare INTEGER(iwp), INTENT(IN) :: maxfactor INTEGER(iwp), DIMENSION(*), INTENT(OUT) :: perm ! !-- Local scalars COMPLEX(wp) :: ck INTEGER(iwp):: ii, ispan INTEGER(iwp):: j, jc, jj INTEGER(iwp):: k, kk, kspan, kt, k1, k2, k3 INTEGER(iwp):: nn, nt ! !-- Permute the results to normal order---done in two stages !-- Permutation for square factors of n nt = ntotal nn = nt - 1 kt = nsquare kspan = nspan jc = nspan / npass perm (1) = nspan IF (kt > 0) THEN k = kt + kt + 1 IF (nfactor < k) k = k - 1 j = 1 perm (k + 1) = jc DO perm (j + 1) = perm (j) / factor(j) perm (k) = perm (k + 1) * factor(j) j = j + 1 k = k - 1 IF (j >= k) EXIT END DO k3 = perm (k + 1) kspan = perm (2) kk = jc + 1 k2 = kspan + 1 j = 1 IF (npass /= ntotal) THEN permute_multi: DO DO DO k = kk + jc DO ! !-- Swap array(kk) <> array(k2) ck = array(kk) array(kk) = array(k2) array(k2) = ck kk = kk + 1 k2 = k2 + 1 IF (kk >= k) EXIT END DO kk = kk + nspan - jc k2 = k2 + nspan - jc IF (kk >= nt) EXIT END DO kk = kk - nt + jc k2 = k2 - nt + kspan IF (k2 >= nspan) EXIT END DO DO DO k2 = k2 - perm (j) j = j + 1 k2 = perm (j + 1) + k2 IF (k2 <= perm (j)) EXIT END DO j = 1 DO IF (kk < k2) CYCLE permute_multi kk = kk + jc k2 = k2 + kspan IF (k2 >= nspan) EXIT END DO IF (kk >= nspan) EXIT END DO EXIT END DO permute_multi ELSE permute_single: DO DO ! !-- Swap array(kk) <> array(k2) ck = array(kk) array(kk) = array(k2) array(k2) = ck kk = kk + 1 k2 = k2 + kspan IF (k2 >= nspan) EXIT END DO DO DO k2 = k2 - perm (j) j = j + 1 k2 = perm (j + 1) + k2 IF (k2 <= perm (j)) EXIT END DO j = 1 DO IF (kk < k2) CYCLE permute_single kk = kk + 1 k2 = k2 + kspan IF (k2 >= nspan) EXIT END DO IF (kk >= nspan) EXIT END DO EXIT END DO permute_single END IF jc = k3 END IF IF (ISHFT(kt, 1) + 1 >= nfactor) RETURN ispan = perm (kt + 1) ! !-- Permutation for square-free factors of n j = nfactor - kt factor(j + 1) = 1 DO factor(j) = factor(j) * factor(j+1) j = j - 1 IF (j == kt) EXIT END DO kt = kt + 1 nn = factor(kt) - 1 j = 0 jj = 0 DO k = kt + 1 k2 = factor(kt) kk = factor(k) j = j + 1 IF (j > nn) EXIT !-- exit infinite loop jj = jj + kk DO WHILE (jj >= k2) jj = jj - k2 k2 = kk k = k + 1 kk = factor(k) jj = jj + kk END DO perm (j) = jj END DO ! !-- Determine the permutation cycles of length greater than 1 j = 0 DO DO j = j + 1 kk = perm(j) IF (kk >= 0) EXIT END DO IF (kk /= j) THEN DO k = kk kk = perm (k) perm (k) = -kk IF (kk == j) EXIT END DO k3 = kk ELSE perm (j) = -j IF (j == nn) EXIT !-- exit infinite loop END IF END DO ! !-- Reorder a and b, following the permutation cycles DO j = k3 + 1 nt = nt - ispan ii = nt - 1 + 1 IF (nt < 0) EXIT !-- exit infinite loop DO DO j = j-1 IF (perm(j) >= 0) EXIT END DO jj = jc DO kspan = jj IF (jj > maxfactor) kspan = maxfactor jj = jj - kspan k = perm(j) kk = jc * k + ii + jj k1 = kk + kspan k2 = 0 DO k2 = k2 + 1 ctmp(k2) = array(k1) k1 = k1 - 1 IF (k1 == kk) EXIT END DO DO k1 = kk + kspan k2 = k1 - jc * (k + perm(k)) k = -perm(k) DO array(k1) = array(k2) k1 = k1 - 1 k2 = k2 - 1 IF (k1 == kk) EXIT END DO kk = k2 IF (k == j) EXIT END DO k1 = kk + kspan k2 = 0 DO k2 = k2 + 1 array(k1) = ctmp(k2) k1 = k1 - 1 IF (k1 == kk) EXIT END DO IF (jj == 0) EXIT END DO IF (j == 1) EXIT END DO END DO END SUBROUTINE permute END SUBROUTINE fftradix END MODULE singleton