summaryrefslogtreecommitdiff
path: root/2.3-1/src/fortran/lapack/zgeqpf.f
diff options
context:
space:
mode:
authorSiddhesh Wani2015-05-25 14:46:31 +0530
committerSiddhesh Wani2015-05-25 14:46:31 +0530
commit6a320264c2de3d6dd8cc1d1327b3c30df4c8cb26 (patch)
tree1b7bd89fdcfd01715713d8a15db471dc75a96bbf /2.3-1/src/fortran/lapack/zgeqpf.f
downloadScilab2C-6a320264c2de3d6dd8cc1d1327b3c30df4c8cb26.tar.gz
Scilab2C-6a320264c2de3d6dd8cc1d1327b3c30df4c8cb26.tar.bz2
Scilab2C-6a320264c2de3d6dd8cc1d1327b3c30df4c8cb26.zip
Original Version
Diffstat (limited to '2.3-1/src/fortran/lapack/zgeqpf.f')
-rw-r--r--2.3-1/src/fortran/lapack/zgeqpf.f234
1 files changed, 234 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/lapack/zgeqpf.f b/2.3-1/src/fortran/lapack/zgeqpf.f
new file mode 100644
index 00000000..6d4f86f0
--- /dev/null
+++ b/2.3-1/src/fortran/lapack/zgeqpf.f
@@ -0,0 +1,234 @@
+ SUBROUTINE ZGEQPF( M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO )
+*
+* -- LAPACK deprecated driver routine (version 3.1) --
+* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
+* November 2006
+*
+* .. Scalar Arguments ..
+ INTEGER INFO, LDA, M, N
+* ..
+* .. Array Arguments ..
+ INTEGER JPVT( * )
+ DOUBLE PRECISION RWORK( * )
+ COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * )
+* ..
+*
+* Purpose
+* =======
+*
+* This routine is deprecated and has been replaced by routine ZGEQP3.
+*
+* ZGEQPF computes a QR factorization with column pivoting of a
+* complex M-by-N matrix A: A*P = Q*R.
+*
+* Arguments
+* =========
+*
+* M (input) INTEGER
+* The number of rows of the matrix A. M >= 0.
+*
+* N (input) INTEGER
+* The number of columns of the matrix A. N >= 0
+*
+* A (input/output) COMPLEX*16 array, dimension (LDA,N)
+* On entry, the M-by-N matrix A.
+* On exit, the upper triangle of the array contains the
+* min(M,N)-by-N upper triangular matrix R; the elements
+* below the diagonal, together with the array TAU,
+* represent the unitary matrix Q as a product of
+* min(m,n) elementary reflectors.
+*
+* LDA (input) INTEGER
+* The leading dimension of the array A. LDA >= max(1,M).
+*
+* JPVT (input/output) INTEGER array, dimension (N)
+* On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted
+* to the front of A*P (a leading column); if JPVT(i) = 0,
+* the i-th column of A is a free column.
+* On exit, if JPVT(i) = k, then the i-th column of A*P
+* was the k-th column of A.
+*
+* TAU (output) COMPLEX*16 array, dimension (min(M,N))
+* The scalar factors of the elementary reflectors.
+*
+* WORK (workspace) COMPLEX*16 array, dimension (N)
+*
+* RWORK (workspace) DOUBLE PRECISION array, dimension (2*N)
+*
+* INFO (output) INTEGER
+* = 0: successful exit
+* < 0: if INFO = -i, the i-th argument had an illegal value
+*
+* Further Details
+* ===============
+*
+* The matrix Q is represented as a product of elementary reflectors
+*
+* Q = H(1) H(2) . . . H(n)
+*
+* Each H(i) has the form
+*
+* H = I - tau * v * v'
+*
+* where tau is a complex scalar, and v is a complex vector with
+* v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i).
+*
+* The matrix P is represented in jpvt as follows: If
+* jpvt(j) = i
+* then the jth column of P is the ith canonical unit vector.
+*
+* Partial column norm updating strategy modified by
+* Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
+* University of Zagreb, Croatia.
+* June 2006.
+* For more details see LAPACK Working Note 176.
+*
+* =====================================================================
+*
+* .. Parameters ..
+ DOUBLE PRECISION ZERO, ONE
+ PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 )
+* ..
+* .. Local Scalars ..
+ INTEGER I, ITEMP, J, MA, MN, PVT
+ DOUBLE PRECISION TEMP, TEMP2, TOL3Z
+ COMPLEX*16 AII
+* ..
+* .. External Subroutines ..
+ EXTERNAL XERBLA, ZGEQR2, ZLARF, ZLARFG, ZSWAP, ZUNM2R
+* ..
+* .. Intrinsic Functions ..
+ INTRINSIC ABS, DCMPLX, DCONJG, MAX, MIN, SQRT
+* ..
+* .. External Functions ..
+ INTEGER IDAMAX
+ DOUBLE PRECISION DLAMCH, DZNRM2
+ EXTERNAL IDAMAX, DLAMCH, DZNRM2
+* ..
+* .. Executable Statements ..
+*
+* Test the input arguments
+*
+ INFO = 0
+ IF( M.LT.0 ) THEN
+ INFO = -1
+ ELSE IF( N.LT.0 ) THEN
+ INFO = -2
+ ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
+ INFO = -4
+ END IF
+ IF( INFO.NE.0 ) THEN
+ CALL XERBLA( 'ZGEQPF', -INFO )
+ RETURN
+ END IF
+*
+ MN = MIN( M, N )
+ TOL3Z = SQRT(DLAMCH('Epsilon'))
+*
+* Move initial columns up front
+*
+ ITEMP = 1
+ DO 10 I = 1, N
+ IF( JPVT( I ).NE.0 ) THEN
+ IF( I.NE.ITEMP ) THEN
+ CALL ZSWAP( M, A( 1, I ), 1, A( 1, ITEMP ), 1 )
+ JPVT( I ) = JPVT( ITEMP )
+ JPVT( ITEMP ) = I
+ ELSE
+ JPVT( I ) = I
+ END IF
+ ITEMP = ITEMP + 1
+ ELSE
+ JPVT( I ) = I
+ END IF
+ 10 CONTINUE
+ ITEMP = ITEMP - 1
+*
+* Compute the QR factorization and update remaining columns
+*
+ IF( ITEMP.GT.0 ) THEN
+ MA = MIN( ITEMP, M )
+ CALL ZGEQR2( M, MA, A, LDA, TAU, WORK, INFO )
+ IF( MA.LT.N ) THEN
+ CALL ZUNM2R( 'Left', 'Conjugate transpose', M, N-MA, MA, A,
+ $ LDA, TAU, A( 1, MA+1 ), LDA, WORK, INFO )
+ END IF
+ END IF
+*
+ IF( ITEMP.LT.MN ) THEN
+*
+* Initialize partial column norms. The first n elements of
+* work store the exact column norms.
+*
+ DO 20 I = ITEMP + 1, N
+ RWORK( I ) = DZNRM2( M-ITEMP, A( ITEMP+1, I ), 1 )
+ RWORK( N+I ) = RWORK( I )
+ 20 CONTINUE
+*
+* Compute factorization
+*
+ DO 40 I = ITEMP + 1, MN
+*
+* Determine ith pivot column and swap if necessary
+*
+ PVT = ( I-1 ) + IDAMAX( N-I+1, RWORK( I ), 1 )
+*
+ IF( PVT.NE.I ) THEN
+ CALL ZSWAP( M, A( 1, PVT ), 1, A( 1, I ), 1 )
+ ITEMP = JPVT( PVT )
+ JPVT( PVT ) = JPVT( I )
+ JPVT( I ) = ITEMP
+ RWORK( PVT ) = RWORK( I )
+ RWORK( N+PVT ) = RWORK( N+I )
+ END IF
+*
+* Generate elementary reflector H(i)
+*
+ AII = A( I, I )
+ CALL ZLARFG( M-I+1, AII, A( MIN( I+1, M ), I ), 1,
+ $ TAU( I ) )
+ A( I, I ) = AII
+*
+ IF( I.LT.N ) THEN
+*
+* Apply H(i) to A(i:m,i+1:n) from the left
+*
+ AII = A( I, I )
+ A( I, I ) = DCMPLX( ONE )
+ CALL ZLARF( 'Left', M-I+1, N-I, A( I, I ), 1,
+ $ DCONJG( TAU( I ) ), A( I, I+1 ), LDA, WORK )
+ A( I, I ) = AII
+ END IF
+*
+* Update partial column norms
+*
+ DO 30 J = I + 1, N
+ IF( RWORK( J ).NE.ZERO ) THEN
+*
+* NOTE: The following 4 lines follow from the analysis in
+* Lapack Working Note 176.
+*
+ TEMP = ABS( A( I, J ) ) / RWORK( J )
+ TEMP = MAX( ZERO, ( ONE+TEMP )*( ONE-TEMP ) )
+ TEMP2 = TEMP*( RWORK( J ) / RWORK( N+J ) )**2
+ IF( TEMP2 .LE. TOL3Z ) THEN
+ IF( M-I.GT.0 ) THEN
+ RWORK( J ) = DZNRM2( M-I, A( I+1, J ), 1 )
+ RWORK( N+J ) = RWORK( J )
+ ELSE
+ RWORK( J ) = ZERO
+ RWORK( N+J ) = ZERO
+ END IF
+ ELSE
+ RWORK( J ) = RWORK( J )*SQRT( TEMP )
+ END IF
+ END IF
+ 30 CONTINUE
+*
+ 40 CONTINUE
+ END IF
+ RETURN
+*
+* End of ZGEQPF
+*
+ END