Annotation of rpl/lapack/lapack/dzsum1.f, revision 1.1
1.1 ! bertrand 1: DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
! 2: *
! 3: * -- LAPACK auxiliary routine (version 3.2) --
! 4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 6: * November 2006
! 7: *
! 8: * .. Scalar Arguments ..
! 9: INTEGER INCX, N
! 10: * ..
! 11: * .. Array Arguments ..
! 12: COMPLEX*16 CX( * )
! 13: * ..
! 14: *
! 15: * Purpose
! 16: * =======
! 17: *
! 18: * DZSUM1 takes the sum of the absolute values of a complex
! 19: * vector and returns a double precision result.
! 20: *
! 21: * Based on DZASUM from the Level 1 BLAS.
! 22: * The change is to use the 'genuine' absolute value.
! 23: *
! 24: * Contributed by Nick Higham for use with ZLACON.
! 25: *
! 26: * Arguments
! 27: * =========
! 28: *
! 29: * N (input) INTEGER
! 30: * The number of elements in the vector CX.
! 31: *
! 32: * CX (input) COMPLEX*16 array, dimension (N)
! 33: * The vector whose elements will be summed.
! 34: *
! 35: * INCX (input) INTEGER
! 36: * The spacing between successive values of CX. INCX > 0.
! 37: *
! 38: * =====================================================================
! 39: *
! 40: * .. Local Scalars ..
! 41: INTEGER I, NINCX
! 42: DOUBLE PRECISION STEMP
! 43: * ..
! 44: * .. Intrinsic Functions ..
! 45: INTRINSIC ABS
! 46: * ..
! 47: * .. Executable Statements ..
! 48: *
! 49: DZSUM1 = 0.0D0
! 50: STEMP = 0.0D0
! 51: IF( N.LE.0 )
! 52: $ RETURN
! 53: IF( INCX.EQ.1 )
! 54: $ GO TO 20
! 55: *
! 56: * CODE FOR INCREMENT NOT EQUAL TO 1
! 57: *
! 58: NINCX = N*INCX
! 59: DO 10 I = 1, NINCX, INCX
! 60: *
! 61: * NEXT LINE MODIFIED.
! 62: *
! 63: STEMP = STEMP + ABS( CX( I ) )
! 64: 10 CONTINUE
! 65: DZSUM1 = STEMP
! 66: RETURN
! 67: *
! 68: * CODE FOR INCREMENT EQUAL TO 1
! 69: *
! 70: 20 CONTINUE
! 71: DO 30 I = 1, N
! 72: *
! 73: * NEXT LINE MODIFIED.
! 74: *
! 75: STEMP = STEMP + ABS( CX( I ) )
! 76: 30 CONTINUE
! 77: DZSUM1 = STEMP
! 78: RETURN
! 79: *
! 80: * End of DZSUM1
! 81: *
! 82: END
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