DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX ) * * -- LAPACK auxiliary routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. INTEGER INCX, N * .. * .. Array Arguments .. COMPLEX*16 CX( * ) * .. * * Purpose * ======= * * DZSUM1 takes the sum of the absolute values of a complex * vector and returns a double precision result. * * Based on DZASUM from the Level 1 BLAS. * The change is to use the 'genuine' absolute value. * * Contributed by Nick Higham for use with ZLACON. * * Arguments * ========= * * N (input) INTEGER * The number of elements in the vector CX. * * CX (input) COMPLEX*16 array, dimension (N) * The vector whose elements will be summed. * * INCX (input) INTEGER * The spacing between successive values of CX. INCX > 0. * * ===================================================================== * * .. Local Scalars .. INTEGER I, NINCX DOUBLE PRECISION STEMP * .. * .. Intrinsic Functions .. INTRINSIC ABS * .. * .. Executable Statements .. * DZSUM1 = 0.0D0 STEMP = 0.0D0 IF( N.LE.0 ) \$ RETURN IF( INCX.EQ.1 ) \$ GO TO 20 * * CODE FOR INCREMENT NOT EQUAL TO 1 * NINCX = N*INCX DO 10 I = 1, NINCX, INCX * * NEXT LINE MODIFIED. * STEMP = STEMP + ABS( CX( I ) ) 10 CONTINUE DZSUM1 = STEMP RETURN * * CODE FOR INCREMENT EQUAL TO 1 * 20 CONTINUE DO 30 I = 1, N * * NEXT LINE MODIFIED. * STEMP = STEMP + ABS( CX( I ) ) 30 CONTINUE DZSUM1 = STEMP RETURN * * End of DZSUM1 * END