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Diffstat (limited to '2.3-1/src/fortran/lapack/zdrscl.f')
| -rw-r--r-- | 2.3-1/src/fortran/lapack/zdrscl.f | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/lapack/zdrscl.f b/2.3-1/src/fortran/lapack/zdrscl.f new file mode 100644 index 00000000..11686d0b --- /dev/null +++ b/2.3-1/src/fortran/lapack/zdrscl.f @@ -0,0 +1,114 @@ + SUBROUTINE ZDRSCL( N, SA, SX, INCX ) +* +* -- LAPACK auxiliary routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + INTEGER INCX, N + DOUBLE PRECISION SA +* .. +* .. Array Arguments .. + COMPLEX*16 SX( * ) +* .. +* +* Purpose +* ======= +* +* ZDRSCL multiplies an n-element complex vector x by the real scalar +* 1/a. This is done without overflow or underflow as long as +* the final result x/a does not overflow or underflow. +* +* Arguments +* ========= +* +* N (input) INTEGER +* The number of components of the vector x. +* +* SA (input) DOUBLE PRECISION +* The scalar a which is used to divide each component of x. +* SA must be >= 0, or the subroutine will divide by zero. +* +* SX (input/output) COMPLEX*16 array, dimension +* (1+(N-1)*abs(INCX)) +* The n-element vector x. +* +* INCX (input) INTEGER +* The increment between successive values of the vector SX. +* > 0: SX(1) = X(1) and SX(1+(i-1)*INCX) = x(i), 1< i<= n +* +* ===================================================================== +* +* .. Parameters .. + DOUBLE PRECISION ZERO, ONE + PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 ) +* .. +* .. Local Scalars .. + LOGICAL DONE + DOUBLE PRECISION BIGNUM, CDEN, CDEN1, CNUM, CNUM1, MUL, SMLNUM +* .. +* .. External Functions .. + DOUBLE PRECISION DLAMCH + EXTERNAL DLAMCH +* .. +* .. External Subroutines .. + EXTERNAL DLABAD, ZDSCAL +* .. +* .. Intrinsic Functions .. + INTRINSIC ABS +* .. +* .. Executable Statements .. +* +* Quick return if possible +* + IF( N.LE.0 ) + $ RETURN +* +* Get machine parameters +* + SMLNUM = DLAMCH( 'S' ) + BIGNUM = ONE / SMLNUM + CALL DLABAD( SMLNUM, BIGNUM ) +* +* Initialize the denominator to SA and the numerator to 1. +* + CDEN = SA + CNUM = ONE +* + 10 CONTINUE + CDEN1 = CDEN*SMLNUM + CNUM1 = CNUM / BIGNUM + IF( ABS( CDEN1 ).GT.ABS( CNUM ) .AND. CNUM.NE.ZERO ) THEN +* +* Pre-multiply X by SMLNUM if CDEN is large compared to CNUM. +* + MUL = SMLNUM + DONE = .FALSE. + CDEN = CDEN1 + ELSE IF( ABS( CNUM1 ).GT.ABS( CDEN ) ) THEN +* +* Pre-multiply X by BIGNUM if CDEN is small compared to CNUM. +* + MUL = BIGNUM + DONE = .FALSE. + CNUM = CNUM1 + ELSE +* +* Multiply X by CNUM / CDEN and return. +* + MUL = CNUM / CDEN + DONE = .TRUE. + END IF +* +* Scale the vector X by MUL +* + CALL ZDSCAL( N, MUL, SX, INCX ) +* + IF( .NOT.DONE ) + $ GO TO 10 +* + RETURN +* +* End of ZDRSCL +* + END |