/*! @file dzsum1.c * \brief Takes sum of the absolute values of a complex vector and returns a double precision result * *
* -- LAPACK auxiliary routine (version 2.0) -- * Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., * Courant Institute, Argonne National Lab, and Rice University * October 31, 1992 **/ #include "slu_dcomplex.h" #include "slu_Cnames.h" /*! \brief
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) INT The number of elements in the vector CX. CX (input) COMPLEX*16 array, dimension (N) The vector whose elements will be summed. INCX (input) INT The spacing between successive values of CX. INCX > 0. =====================================================================*/ double dzsum1_(int *n, doublecomplex *cx, int *incx) { /* Builtin functions */ double z_abs(doublecomplex *); /* Local variables */ int i, nincx; double stemp; #define CX(I) cx[(I)-1] stemp = 0.; if (*n <= 0) { return stemp; } if (*incx == 1) { goto L20; } /* CODE FOR INCREMENT NOT EQUAL TO 1 */ nincx = *n * *incx; for (i = 1; *incx < 0 ? i >= nincx : i <= nincx; i += *incx) { /* NEXT LINE MODIFIED. */ stemp += z_abs(&CX(i)); /* L10: */ } return stemp; /* CODE FOR INCREMENT EQUAL TO 1 */ L20: for (i = 1; i <= *n; ++i) { /* NEXT LINE MODIFIED. */ stemp += z_abs(&CX(i)); /* L30: */ } return stemp; /* End of DZSUM1 */ } /* dzsum1_ */