323 lines
7.9 KiB
Fortran
323 lines
7.9 KiB
Fortran
c\BeginDoc
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c
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c\Name: zsortc
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c
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c\Description:
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c Sorts the Complex*16 array in X into the order
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c specified by WHICH and optionally applies the permutation to the
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c Double precision array Y.
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c
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c\Usage:
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c call zsortc
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c ( WHICH, APPLY, N, X, Y )
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c
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c\Arguments
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c WHICH Character*2. (Input)
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c 'LM' -> sort X into increasing order of magnitude.
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c 'SM' -> sort X into decreasing order of magnitude.
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c 'LR' -> sort X with real(X) in increasing algebraic order
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c 'SR' -> sort X with real(X) in decreasing algebraic order
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c 'LI' -> sort X with imag(X) in increasing algebraic order
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c 'SI' -> sort X with imag(X) in decreasing algebraic order
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c
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c APPLY Logical. (Input)
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c APPLY = .TRUE. -> apply the sorted order to array Y.
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c APPLY = .FALSE. -> do not apply the sorted order to array Y.
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c
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c N Integer. (INPUT)
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c Size of the arrays.
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c
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c X Complex*16 array of length N. (INPUT/OUTPUT)
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c This is the array to be sorted.
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c
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c Y Complex*16 array of length N. (INPUT/OUTPUT)
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c
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c\EndDoc
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c
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c-----------------------------------------------------------------------
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c
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c\BeginLib
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c
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c\Routines called:
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c dlapy2 LAPACK routine to compute sqrt(x**2+y**2) carefully.
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c
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c\Author
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c Danny Sorensen Phuong Vu
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c Richard Lehoucq CRPC / Rice University
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c Dept. of Computational & Houston, Texas
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c Applied Mathematics
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c Rice University
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c Houston, Texas
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c
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c Adapted from the sort routine in LANSO.
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c
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c\SCCS Information: @(#)
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c FILE: sortc.F SID: 2.2 DATE OF SID: 4/20/96 RELEASE: 2
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c
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c\EndLib
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c
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c-----------------------------------------------------------------------
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c
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subroutine zsortc (which, apply, n, x, y)
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c
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c %------------------%
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c | Scalar Arguments |
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c %------------------%
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c
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character*2 which
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logical apply
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integer n
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c
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c %-----------------%
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c | Array Arguments |
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c %-----------------%
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c
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Complex*16
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& x(0:n-1), y(0:n-1)
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c
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c %---------------%
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c | Local Scalars |
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c %---------------%
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c
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integer i, igap, j
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Complex*16
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& temp
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Double precision
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& temp1, temp2
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c
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c %--------------------%
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c | External functions |
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c %--------------------%
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c
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Double precision
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& dlapy2
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c
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c %--------------------%
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c | Intrinsic Functions |
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c %--------------------%
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Intrinsic
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& dble, dimag
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c
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c %-----------------------%
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c | Executable Statements |
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c %-----------------------%
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c
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igap = n / 2
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c
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if (which .eq. 'LM') then
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c
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c %--------------------------------------------%
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c | Sort X into increasing order of magnitude. |
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c %--------------------------------------------%
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c
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10 continue
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if (igap .eq. 0) go to 9000
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c
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do 30 i = igap, n-1
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j = i-igap
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20 continue
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c
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if (j.lt.0) go to 30
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c
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temp1 = dlapy2(dble(x(j)),dimag(x(j)))
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temp2 = dlapy2(dble(x(j+igap)),dimag(x(j+igap)))
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c
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if (temp1.gt.temp2) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 30
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end if
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j = j-igap
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go to 20
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30 continue
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igap = igap / 2
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go to 10
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c
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else if (which .eq. 'SM') then
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c
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c %--------------------------------------------%
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c | Sort X into decreasing order of magnitude. |
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c %--------------------------------------------%
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c
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40 continue
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if (igap .eq. 0) go to 9000
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c
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do 60 i = igap, n-1
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j = i-igap
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50 continue
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c
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if (j .lt. 0) go to 60
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c
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temp1 = dlapy2(dble(x(j)),dimag(x(j)))
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temp2 = dlapy2(dble(x(j+igap)),dimag(x(j+igap)))
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c
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if (temp1.lt.temp2) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 60
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endif
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j = j-igap
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go to 50
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60 continue
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igap = igap / 2
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go to 40
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c
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else if (which .eq. 'LR') then
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c
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c %------------------------------------------------%
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c | Sort XREAL into increasing order of algebraic. |
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c %------------------------------------------------%
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c
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70 continue
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if (igap .eq. 0) go to 9000
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c
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do 90 i = igap, n-1
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j = i-igap
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80 continue
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c
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if (j.lt.0) go to 90
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c
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if (dble(x(j)).gt.dble(x(j+igap))) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 90
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endif
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j = j-igap
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go to 80
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90 continue
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igap = igap / 2
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go to 70
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c
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else if (which .eq. 'SR') then
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c
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c %------------------------------------------------%
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c | Sort XREAL into decreasing order of algebraic. |
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c %------------------------------------------------%
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c
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100 continue
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if (igap .eq. 0) go to 9000
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do 120 i = igap, n-1
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j = i-igap
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110 continue
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c
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if (j.lt.0) go to 120
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c
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if (dble(x(j)).lt.dble(x(j+igap))) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 120
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endif
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j = j-igap
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go to 110
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120 continue
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igap = igap / 2
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go to 100
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c
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else if (which .eq. 'LI') then
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c
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c %--------------------------------------------%
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c | Sort XIMAG into increasing algebraic order |
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c %--------------------------------------------%
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c
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130 continue
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if (igap .eq. 0) go to 9000
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do 150 i = igap, n-1
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j = i-igap
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140 continue
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c
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if (j.lt.0) go to 150
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c
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if (dimag(x(j)).gt.dimag(x(j+igap))) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 150
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endif
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j = j-igap
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go to 140
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150 continue
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igap = igap / 2
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go to 130
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c
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else if (which .eq. 'SI') then
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c
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c %---------------------------------------------%
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c | Sort XIMAG into decreasing algebraic order |
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c %---------------------------------------------%
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c
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160 continue
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if (igap .eq. 0) go to 9000
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do 180 i = igap, n-1
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j = i-igap
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170 continue
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c
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if (j.lt.0) go to 180
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c
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if (dimag(x(j)).lt.dimag(x(j+igap))) then
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temp = x(j)
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x(j) = x(j+igap)
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x(j+igap) = temp
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c
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if (apply) then
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temp = y(j)
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y(j) = y(j+igap)
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y(j+igap) = temp
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end if
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else
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go to 180
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endif
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j = j-igap
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go to 170
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180 continue
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igap = igap / 2
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go to 160
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end if
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c
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9000 continue
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return
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c
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c %---------------%
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c | End of zsortc |
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c %---------------%
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c
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end
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