00001 DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX ) 00002 * 00003 * -- LAPACK auxiliary routine (version 3.2) -- 00004 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00005 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00006 * November 2006 00007 * 00008 * .. Scalar Arguments .. 00009 INTEGER INCX, N 00010 * .. 00011 * .. Array Arguments .. 00012 COMPLEX*16 CX( * ) 00013 * .. 00014 * 00015 * Purpose 00016 * ======= 00017 * 00018 * DZSUM1 takes the sum of the absolute values of a complex 00019 * vector and returns a double precision result. 00020 * 00021 * Based on DZASUM from the Level 1 BLAS. 00022 * The change is to use the 'genuine' absolute value. 00023 * 00024 * Contributed by Nick Higham for use with ZLACON. 00025 * 00026 * Arguments 00027 * ========= 00028 * 00029 * N (input) INTEGER 00030 * The number of elements in the vector CX. 00031 * 00032 * CX (input) COMPLEX*16 array, dimension (N) 00033 * The vector whose elements will be summed. 00034 * 00035 * INCX (input) INTEGER 00036 * The spacing between successive values of CX. INCX > 0. 00037 * 00038 * ===================================================================== 00039 * 00040 * .. Local Scalars .. 00041 INTEGER I, NINCX 00042 DOUBLE PRECISION STEMP 00043 * .. 00044 * .. Intrinsic Functions .. 00045 INTRINSIC ABS 00046 * .. 00047 * .. Executable Statements .. 00048 * 00049 DZSUM1 = 0.0D0 00050 STEMP = 0.0D0 00051 IF( N.LE.0 ) 00052 $ RETURN 00053 IF( INCX.EQ.1 ) 00054 $ GO TO 20 00055 * 00056 * CODE FOR INCREMENT NOT EQUAL TO 1 00057 * 00058 NINCX = N*INCX 00059 DO 10 I = 1, NINCX, INCX 00060 * 00061 * NEXT LINE MODIFIED. 00062 * 00063 STEMP = STEMP + ABS( CX( I ) ) 00064 10 CONTINUE 00065 DZSUM1 = STEMP 00066 RETURN 00067 * 00068 * CODE FOR INCREMENT EQUAL TO 1 00069 * 00070 20 CONTINUE 00071 DO 30 I = 1, N 00072 * 00073 * NEXT LINE MODIFIED. 00074 * 00075 STEMP = STEMP + ABS( CX( I ) ) 00076 30 CONTINUE 00077 DZSUM1 = STEMP 00078 RETURN 00079 * 00080 * End of DZSUM1 00081 * 00082 END
1.7.2