OpenBLAS/lapack/potf2/zpotf2_U.c

/*********************************************************************/
/* Copyright 2009, 2010 The University of Texas at Austin.           */
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#include <stdio.h>
#include <math.h>
#include "common.h"

static FLOAT dm1 = -1.;

#ifndef SQRT
#define SQRT(x)	sqrt(x)
#endif

blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa, FLOAT *sb, BLASLONG myid) {

  BLASLONG n, lda;
  FLOAT *a;

  FLOAT ajj;
  BLASLONG i, j;

  n      = args -> n;
  a      = (FLOAT *)args -> a;
  lda    = args -> lda;

  if (range_n) {
    n      = range_n[1] - range_n[0];
    a     += range_n[0] * (lda + 1) * COMPSIZE;
  }

  for (j = 0; j < n; j++) {

    ajj = CREAL(DOTC_K(j, a, 1, a, 1));

    ajj = *(a + j * 2) - ajj;

    if (ajj <= 0){
      *(a + j * 2 + 0) = ajj;
      *(a + j * 2 + 1) = ZERO;
      return j + 1;
    }

    ajj = SQRT(ajj);
    *(a + j * 2 + 0)  = ajj;
    *(a + j * 2 + 1)  = ZERO;

    i = n - j - 1;

    if (i > 0){
      GEMV_U(j, i, 0, dm1, ZERO,
	      a + lda * 2, lda,
	      a, 1,
	      a + (j + lda) * 2, lda, sb);

      SCAL_K(i, 0, 0, ONE / ajj, ZERO,
	      a + (j + lda) * 2, lda, NULL, 0, NULL, 0);
    }

    a += 2 * lda;
  }

  return 0;
}