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view main/sparse/SuperLU/SRC/icmax1.c @ 0:6b33357c7561 octave-forge
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author | pkienzle |
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date | Wed, 10 Oct 2001 19:54:49 +0000 |
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/* * -- SuperLU routine (version 2.0) -- * Univ. of California Berkeley, Xerox Palo Alto Research Center, * and Lawrence Berkeley National Lab. * November 15, 1997 * */ #include <math.h> #include "scomplex.h" int icmax1_(int *n, complex *cx, int *incx) { /* -- LAPACK auxiliary routine (version 2.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University September 30, 1994 Purpose ======= ICMAX1 finds the index of the element whose real part has maximum absolute value. Based on ICAMAX from Level 1 BLAS. The change is to use the 'genuine' absolute value. Contributed by Nick Higham for use with CLACON. Arguments ========= N (input) INT The number of elements in the vector CX. CX (input) COMPLEX array, dimension (N) The vector whose elements will be summed. INCX (input) INT The spacing between successive values of CX. INCX >= 1. ===================================================================== NEXT LINE IS THE ONLY MODIFICATION. Parameter adjustments Function Body */ /* System generated locals */ int ret_val, i__1, i__2; float r__1; /* Local variables */ static float smax; static int i, ix; #define CX(I) cx[(I)-1] ret_val = 0; if (*n < 1) { return ret_val; } ret_val = 1; if (*n == 1) { return ret_val; } if (*incx == 1) { goto L30; } /* CODE FOR INCREMENT NOT EQUAL TO 1 */ ix = 1; smax = (r__1 = CX(1).r, fabs(r__1)); ix += *incx; i__1 = *n; for (i = 2; i <= *n; ++i) { i__2 = ix; if ((r__1 = CX(ix).r, fabs(r__1)) <= smax) { goto L10; } ret_val = i; i__2 = ix; smax = (r__1 = CX(ix).r, fabs(r__1)); L10: ix += *incx; /* L20: */ } return ret_val; /* CODE FOR INCREMENT EQUAL TO 1 */ L30: smax = (r__1 = CX(1).r, fabs(r__1)); i__1 = *n; for (i = 2; i <= *n; ++i) { i__2 = i; if ((r__1 = CX(i).r, fabs(r__1)) <= smax) { goto L40; } ret_val = i; i__2 = i; smax = (r__1 = CX(i).r, fabs(r__1)); L40: ; } return ret_val; /* End of ICMAX1 */ } /* icmax1_ */